Element: Dosage

The FHIR Dosage element is complex but essential to achieve medicines interoperability. Extensive implementation guidance with numerous clinically appropriate examples are documented within this guide.

Profile
Dictionary

Dosage			BackboneElement	Element id Dosage Short description How the medication is/was taken or should be taken Definition Indicates how the medication is/was taken or should be taken by the patient. Data type BackboneElement Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a rim: .outboundRelationship[typeCode=COMP].target[classCode=SBADM, moodCode=INT]
id		0..1		There are no (further) constraints on this element Element id Dosage.id Short description Unique id for inter-element referencing Definition Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces. Mappings rim: n/a
extension	I	0..*	Extension	There are no (further) constraints on this element Element id Dosage.extension Short description Additional content defined by implementations Alternate names extensions, user content Definition May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Comments There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone. Data type Extension Sliced: Unordered, Open, by url(Value) Extensions are always sliced by (at least) url Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` ext-1: Must have either extensions or value[x], not both `extension.exists() != value.exists()` Mappings rim: n/a rim: N/A
modifierExtension	Σ ?! I	0..*	Extension	There are no (further) constraints on this element Element id Dosage.modifierExtension Short description Extensions that cannot be ignored even if unrecognized Alternate names extensions, user content, modifiers Definition May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions. Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself). Requirements Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions. Comments There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone. Data type Extension Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` ext-1: Must have either extensions or value[x], not both `extension.exists() != value.exists()` Mappings rim: n/a rim: N/A
sequence	Σ	0..1	integer	Element id Dosage.sequence Short description The order of the dosage instructions Definition Indicates the order in which the dosage instructions should be applied or interpreted. Requirements If the sequence number of multiple Dosages is the same, then it is implied that the instructions are to be treated as concurrent. If the sequence number is different, then the Dosages are intended to be sequential. Comments 32 bit number; for values larger than this, use decimal Data type integer Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a v2: TQ1-1 rim: .text
text	Σ	0..1	string	Element id Dosage.text Short description Free text dosage instructions e.g. SIG Definition Free text dosage instructions e.g. SIG. Requirements Free text dosage instructions can be used for cases where the instructions are too complex to code. The content of this attribute does not include the name or description of the medication. When coded instructions are present, the free text instructions may still be present for display to humans taking or administering the medication. It is expected that the text instructions will always be populated. If the dosage.timing attribute is also populated, then the dosage.text should reflect the same information as the timing. Additional information about administration or preparation of the medication should be included as text. Comments Note that FHIR strings SHALL NOT exceed 1MB in size Data type string Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a v2: RXO-6; RXE-21 rim: .text
additionalInstruction	Σ	0..*	CodeableConcept	Element id Dosage.additionalInstruction Short description Supplemental instruction or warnings to the patient - e.g. "with meals", "may cause drowsiness" Definition Supplemental instructions to the patient on how to take the medication (e.g. "with meals" or"take half to one hour before food") or warnings for the patient about the medication (e.g. "may cause drowsiness" or "avoid exposure of skin to direct sunlight or sunlamps"). Requirements Additional instruction is intended to be coded, but where no code exists, the element could include text. For example, "Swallow with plenty of water" which might or might not be coded. Comments Information about administration or preparation of the medication (e.g. "infuse as rapidly as possibly via intraperitoneal port" or "immediately following drug x") should be populated in dosage.text. Data type CodeableConcept Binding A coded concept identifying additional instructions such as "take with water" or "avoid operating heavy machinery". SNOMEDCTAdditionalDosageInstructions (example) Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a v2: CE/CNE/CWE rim: CD orim: fhir:CodeableConcept rdfs:subClassOf dt:CD v2: RXO-7 rim: .text
patientInstruction	Σ	0..1	string	Element id Dosage.patientInstruction Short description Patient or consumer oriented instructions Definition Instructions in terms that are understood by the patient or consumer. Comments Note that FHIR strings SHALL NOT exceed 1MB in size Data type string Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a v2: RXO-7 rim: .text
timing	Σ	0..1	Timing	Element id Dosage.timing Short description When medication should be administered Definition When medication should be administered. Requirements The timing schedule for giving the medication to the patient. This data type allows many different expressions. For example: "Every 8 hours"; "Three times a day"; "1/2 an hour before breakfast for 10 days from 23-Dec 2011:"; "15 Oct 2013, 17 Oct 2013 and 1 Nov 2013". Sometimes, a rate can imply duration when expressed as total volume / duration (e.g. 500mL/2 hours implies a duration of 2 hours). However, when rate doesn't imply duration (e.g. 250mL/hour), then the timing.repeat.duration is needed to convey the infuse over time period. Comments This attribute might not always be populated while the Dosage.text is expected to be populated. If both are populated, then the Dosage.text should reflect the content of the Dosage.timing. Data type Timing Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a v2: N/A rim: QSET<TS> (GTS) rim: .effectiveTime
asNeeded[x]	Σ	0..1		Element id Dosage.asNeeded[x] Short description Take "as needed" (for x) Definition Indicates whether the Medication is only taken when needed within a specific dosing schedule (Boolean option), or it indicates the precondition for taking the Medication (CodeableConcept). Comments Can express "as needed" without a reason by setting the Boolean = True. In this case the CodeableConcept is not populated. Or you can express "as needed" with a reason by including the CodeableConcept. In this case the Boolean is assumed to be True. If you set the Boolean to False, then the dose is given according to the schedule and is not "prn" or "as needed". Binding A coded concept identifying the precondition that should be met or evaluated prior to consuming or administering a medication dose. For example "pain", "30 minutes prior to sexual intercourse", "on flare-up" etc. SNOMEDCTMedicationAsNeededReasonCodes (example) Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a v2: TQ1-9 rim: .outboundRelationship[typeCode=PRCN].target[classCode=OBS, moodCode=EVN, code="as needed"].value=boolean or codable concept
asNeededBoolean			boolean	Data type boolean
asNeededCodeableConcept			CodeableConcept	Data type CodeableConcept
site	Σ	0..1	CodeableConcept	Element id Dosage.site Short description Body site to administer to Definition Body site to administer to. Requirements A coded specification of the anatomic site where the medication first enters the body. Comments If the use case requires attributes from the BodySite resource (e.g. to identify and track separately) then use the standard extension bodySite. May be a summary code, or a reference to a very precise definition of the location, or both. Data type CodeableConcept Binding A coded concept describing the site location the medicine enters into or onto the body. SNOMEDCTAnatomicalStructureForAdministrationSiteCodes (example) Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a v2: CE/CNE/CWE rim: CD orim: fhir:CodeableConcept rdfs:subClassOf dt:CD v2: RXR-2 rim: .approachSiteCode
route	Σ	0..1	CodeableConcept	Element id Dosage.route Short description How drug should enter body Definition How drug should enter body. Requirements A code specifying the route or physiological path of administration of a therapeutic agent into or onto a patient's body. Comments Not all terminology uses fit this general pattern. In some cases, models should not use CodeableConcept and use Coding directly and provide their own structure for managing text, codings, translations and the relationship between elements and pre- and post-coordination. Data type CodeableConcept Binding A coded concept describing the route or physiological path of administration of a therapeutic agent into or onto the body of a subject. SNOMEDCTRouteCodes (example) Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a v2: CE/CNE/CWE rim: CD orim: fhir:CodeableConcept rdfs:subClassOf dt:CD v2: RXR-1 rim: .routeCode
method	Σ	0..1	CodeableConcept	Element id Dosage.method Short description Technique for administering medication Definition Technique for administering medication. Requirements A coded value indicating the method by which the medication is introduced into or onto the body. Most commonly used for injections. For examples, Slow Push; Deep IV. Comments Terminologies used often pre-coordinate this term with the route and or form of administration. Data type CodeableConcept Binding A coded concept describing the technique by which the medicine is administered. SNOMEDCTAdministrationMethodCodes (example) Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a v2: CE/CNE/CWE rim: CD orim: fhir:CodeableConcept rdfs:subClassOf dt:CD v2: RXR-4 rim: .doseQuantity
doseAndRate	Σ	0..*	Element	Element id Dosage.doseAndRate Short description Amount of medication administered Definition The amount of medication administered. Data type Element Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a v2: TQ1-2
id		0..1		There are no (further) constraints on this element Element id Dosage.doseAndRate.id Short description Unique id for inter-element referencing Definition Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces. Mappings rim: n/a
extension	I	0..*	Extension	There are no (further) constraints on this element Element id Dosage.doseAndRate.extension Short description Additional content defined by implementations Alternate names extensions, user content Definition May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Comments There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone. Data type Extension Sliced: Unordered, Open, by url(Value) Extensions are always sliced by (at least) url Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` ext-1: Must have either extensions or value[x], not both `extension.exists() != value.exists()` Mappings rim: n/a rim: N/A
type	Σ	0..1	CodeableConcept	Element id Dosage.doseAndRate.type Short description The kind of dose or rate specified Definition The kind of dose or rate specified, for example, ordered or calculated. Requirements If the type is not populated, assume to be "ordered". Comments Not all terminology uses fit this general pattern. In some cases, models should not use CodeableConcept and use Coding directly and provide their own structure for managing text, codings, translations and the relationship between elements and pre- and post-coordination. Data type CodeableConcept Binding The kind of dose or rate specified. DoseAndRateType (example) Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a v2: CE/CNE/CWE rim: CD orim: fhir:CodeableConcept rdfs:subClassOf dt:CD v2: RXO-21; RXE-23
dose[x]	Σ	0..1		Element id Dosage.doseAndRate.dose[x] Short description Amount of medication per dose Definition Amount of medication per dose. Requirements The amount of therapeutic or other substance given at one administration event. Comments Note that this specifies the quantity of the specified medication, not the quantity for each active ingredient(s). Each ingredient amount can be communicated in the Medication resource. For example, if one wants to communicate that a tablet was 375 mg, where the dose was one tablet, you can use the Medication resource to document that the tablet was comprised of 375 mg of drug XYZ. Alternatively if the dose was 375 mg, then you may only need to use the Medication resource to indicate this was a tablet. If the example were an IV such as dopamine and you wanted to communicate that 400mg of dopamine was mixed in 500 ml of some IV solution, then this would all be communicated in the Medication resource. If the administration is not intended to be instantaneous (rate is present or timing has a duration), this can be specified to convey the total amount to be administered over the period of time as indicated by the schedule e.g. 500 ml in dose, with timing used to convey that this should be done over 4 hours. Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a v2: RXO-2, RXE-3 rim: .doseQuantity
doseRange			Range	Data type Range
doseQuantity			SimpleQuantity	Data type SimpleQuantity
rate[x]	Σ	0..1		Element id Dosage.doseAndRate.rate[x] Short description Amount of medication per unit of time Definition Amount of medication per unit of time. Requirements Identifies the speed with which the medication was or will be introduced into the patient. Typically the rate for an infusion e.g. 100 ml per 1 hour or 100 ml/hr. May also be expressed as a rate per unit of time e.g. 500 ml per 2 hours. Other examples: 200 mcg/min or 200 mcg/1 minute; 1 liter/8 hours. Sometimes, a rate can imply duration when expressed as total volume / duration (e.g. 500mL/2 hours implies a duration of 2 hours). However, when rate doesn't imply duration (e.g. 250mL/hour), then the timing.repeat.duration is needed to convey the infuse over time period. Comments It is possible to supply both a rate and a doseQuantity to provide full details about how the medication is to be administered and supplied. If the rate is intended to change over time, depending on local rules/regulations, each change should be captured as a new version of the MedicationRequest with an updated rate, or captured with a new MedicationRequest with the new rate. It is possible to specify a rate over time (for example, 100 ml/hour) using either the rateRatio and rateQuantity. The rateQuantity approach requires systems to have the capability to parse UCUM grammer where ml/hour is included rather than a specific ratio where the time is specified as the denominator. Where a rate such as 500ml over 2 hours is specified, the use of rateRatio may be more semantically correct than specifying using a rateQuantity of 250 mg/hour. Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` Mappings rim: n/a v2: RXE22, RXE23, RXE-24 rim: .rateQuantity
rateRatio			Ratio	Data type Ratio
rateRange			Range	Data type Range
rateQuantity			SimpleQuantity	Data type SimpleQuantity
maxDosePerPeriod	Σ I	0..1	Ratio	Element id Dosage.maxDosePerPeriod Short description Upper limit on medication per unit of time Definition Upper limit on medication per unit of time. Requirements The maximum total quantity of a therapeutic substance that may be administered to a subject over the period of time. For example, 1000mg in 24 hours. Comments This is intended for use as an adjunct to the dosage when there is an upper cap. For example "2 tablets every 4 hours to a maximum of 8/day". Data type Ratio Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` rat-1: Numerator and denominator SHALL both be present, or both are absent. If both are absent, there SHALL be some extension present `(numerator.empty() xor denominator.exists()) and (numerator.exists() or extension.exists())` Mappings rim: n/a v2: N/A rim: RTO v2: RXO-23, RXE-19 rim: .maxDoseQuantity
maxDosePerAdministration	Σ I	0..1	SimpleQuantity	Element id Dosage.maxDosePerAdministration Short description Upper limit on medication per administration Definition Upper limit on medication per administration. Requirements The maximum total quantity of a therapeutic substance that may be administered to a subject per administration. Comments This is intended for use as an adjunct to the dosage when there is an upper cap. For example, a body surface area related dose with a maximum amount, such as 1.5 mg/m2 (maximum 2 mg) IV over 5 – 10 minutes would have doseQuantity of 1.5 mg/m2 and maxDosePerAdministration of 2 mg. Data type SimpleQuantity Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` qty-3: If a code for the unit is present, the system SHALL also be present `code.empty() or system.exists()` sqty-1: The comparator is not used on a SimpleQuantity `comparator.empty()` Mappings rim: n/a v2: SN (see also Range) or CQ rim: PQ, IVL<PQ>, MO, CO, depending on the values rim: not supported
maxDosePerLifetime	Σ I	0..1	SimpleQuantity	Element id Dosage.maxDosePerLifetime Short description Upper limit on medication per lifetime of the patient Definition Upper limit on medication per lifetime of the patient. Requirements The maximum total quantity of a therapeutic substance that may be administered per lifetime of the subject. Comments The context of use may frequently define what kind of quantity this is and therefore what kind of units can be used. The context of use may also restrict the values for the comparator. Data type SimpleQuantity Constraints ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` qty-3: If a code for the unit is present, the system SHALL also be present `code.empty() or system.exists()` sqty-1: The comparator is not used on a SimpleQuantity `comparator.empty()` Mappings rim: n/a v2: SN (see also Range) or CQ rim: PQ, IVL<PQ>, MO, CO, depending on the values rim: not supported

Dosage
Definition	Indicates how the medication is/was taken or should be taken by the patient.
Cardinality	0...*
Invariants	ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())`
Mappings	rim: n/a rim: .outboundRelationship[typeCode=COMP].target[classCode=SBADM, moodCode=INT]
Dosage.id
Definition	Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.
Cardinality	0...1
Type
Mappings	rim: n/a
Dosage.extension
Definition	May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.
Cardinality	0...*
Type	Extension
Alias	extensions, user content
Comments	There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.
Slicing	Unordered, Open, by url(Value)
Invariants	ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` ext-1: Must have either extensions or value[x], not both `extension.exists() != value.exists()`
Mappings	rim: n/a rim: N/A
Dosage.modifierExtension
Definition	May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions. Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).
Cardinality	0...*
Type	Extension
Modifier	True
Summary	True
Alias	extensions, user content, modifiers
Requirements	Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions.
Comments	There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.
Invariants	ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` ext-1: Must have either extensions or value[x], not both `extension.exists() != value.exists()`
Mappings	rim: n/a rim: N/A
Dosage.sequence
Definition	Indicates the order in which the dosage instructions should be applied or interpreted.
Cardinality	0...1
Type	integer
Summary	True
Requirements	If the sequence number of multiple Dosages is the same, then it is implied that the instructions are to be treated as concurrent. If the sequence number is different, then the Dosages are intended to be sequential.
Comments	32 bit number; for values larger than this, use decimal
Invariants	ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())`
Mappings	rim: n/a v2: TQ1-1 rim: .text
Dosage.text
Definition	Free text dosage instructions e.g. SIG.
Cardinality	0...1
Type	string
Summary	True
Requirements	Free text dosage instructions can be used for cases where the instructions are too complex to code. The content of this attribute does not include the name or description of the medication. When coded instructions are present, the free text instructions may still be present for display to humans taking or administering the medication. It is expected that the text instructions will always be populated. If the dosage.timing attribute is also populated, then the dosage.text should reflect the same information as the timing. Additional information about administration or preparation of the medication should be included as text.
Comments	Note that FHIR strings SHALL NOT exceed 1MB in size
Invariants	ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())`
Mappings	rim: n/a v2: RXO-6; RXE-21 rim: .text
Dosage.additionalInstruction
Definition	Supplemental instructions to the patient on how to take the medication (e.g. "with meals" or"take half to one hour before food") or warnings for the patient about the medication (e.g. "may cause drowsiness" or "avoid exposure of skin to direct sunlight or sunlamps").
Cardinality	0...*
Type	CodeableConcept
Binding	A coded concept identifying additional instructions such as "take with water" or "avoid operating heavy machinery". SNOMEDCTAdditionalDosageInstructions (example)
Summary	True
Requirements	Additional instruction is intended to be coded, but where no code exists, the element could include text. For example, "Swallow with plenty of water" which might or might not be coded.
Comments	Information about administration or preparation of the medication (e.g. "infuse as rapidly as possibly via intraperitoneal port" or "immediately following drug x") should be populated in dosage.text.
Invariants	ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())`
Mappings	rim: n/a v2: CE/CNE/CWE rim: CD orim: fhir:CodeableConcept rdfs:subClassOf dt:CD v2: RXO-7 rim: .text
Dosage.patientInstruction
Definition	Instructions in terms that are understood by the patient or consumer.
Cardinality	0...1
Type	string
Summary	True
Comments	Note that FHIR strings SHALL NOT exceed 1MB in size
Invariants	ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())`
Mappings	rim: n/a v2: RXO-7 rim: .text
Dosage.timing
Definition	When medication should be administered.
Cardinality	0...1
Type	Timing
Summary	True
Requirements	The timing schedule for giving the medication to the patient. This data type allows many different expressions. For example: "Every 8 hours"; "Three times a day"; "1/2 an hour before breakfast for 10 days from 23-Dec 2011:"; "15 Oct 2013, 17 Oct 2013 and 1 Nov 2013". Sometimes, a rate can imply duration when expressed as total volume / duration (e.g. 500mL/2 hours implies a duration of 2 hours). However, when rate doesn't imply duration (e.g. 250mL/hour), then the timing.repeat.duration is needed to convey the infuse over time period.
Comments	This attribute might not always be populated while the Dosage.text is expected to be populated. If both are populated, then the Dosage.text should reflect the content of the Dosage.timing.
Invariants	ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())`
Mappings	rim: n/a v2: N/A rim: QSET<TS> (GTS) rim: .effectiveTime
Dosage.asNeeded[x]
Definition	Indicates whether the Medication is only taken when needed within a specific dosing schedule (Boolean option), or it indicates the precondition for taking the Medication (CodeableConcept).
Cardinality	0...1
Type	boolean
Binding	A coded concept identifying the precondition that should be met or evaluated prior to consuming or administering a medication dose. For example "pain", "30 minutes prior to sexual intercourse", "on flare-up" etc. SNOMEDCTMedicationAsNeededReasonCodes (example)
Summary	True
Comments	Can express "as needed" without a reason by setting the Boolean = True. In this case the CodeableConcept is not populated. Or you can express "as needed" with a reason by including the CodeableConcept. In this case the Boolean is assumed to be True. If you set the Boolean to False, then the dose is given according to the schedule and is not "prn" or "as needed".
Invariants	ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())`
Mappings	rim: n/a v2: TQ1-9 rim: .outboundRelationship[typeCode=PRCN].target[classCode=OBS, moodCode=EVN, code="as needed"].value=boolean or codable concept
Dosage.site
Definition	Body site to administer to.
Cardinality	0...1
Type	CodeableConcept
Binding	A coded concept describing the site location the medicine enters into or onto the body. SNOMEDCTAnatomicalStructureForAdministrationSiteCodes (example)
Summary	True
Requirements	A coded specification of the anatomic site where the medication first enters the body.
Comments	If the use case requires attributes from the BodySite resource (e.g. to identify and track separately) then use the standard extension bodySite. May be a summary code, or a reference to a very precise definition of the location, or both.
Invariants	ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())`
Mappings	rim: n/a v2: CE/CNE/CWE rim: CD orim: fhir:CodeableConcept rdfs:subClassOf dt:CD v2: RXR-2 rim: .approachSiteCode
Dosage.route
Definition	How drug should enter body.
Cardinality	0...1
Type	CodeableConcept
Binding	A coded concept describing the route or physiological path of administration of a therapeutic agent into or onto the body of a subject. SNOMEDCTRouteCodes (example)
Summary	True
Requirements	A code specifying the route or physiological path of administration of a therapeutic agent into or onto a patient's body.
Comments	Not all terminology uses fit this general pattern. In some cases, models should not use CodeableConcept and use Coding directly and provide their own structure for managing text, codings, translations and the relationship between elements and pre- and post-coordination.
Invariants	ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())`
Mappings	rim: n/a v2: CE/CNE/CWE rim: CD orim: fhir:CodeableConcept rdfs:subClassOf dt:CD v2: RXR-1 rim: .routeCode
Dosage.method
Definition	Technique for administering medication.
Cardinality	0...1
Type	CodeableConcept
Binding	A coded concept describing the technique by which the medicine is administered. SNOMEDCTAdministrationMethodCodes (example)
Summary	True
Requirements	A coded value indicating the method by which the medication is introduced into or onto the body. Most commonly used for injections. For examples, Slow Push; Deep IV.
Comments	Terminologies used often pre-coordinate this term with the route and or form of administration.
Invariants	ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())`
Mappings	rim: n/a v2: CE/CNE/CWE rim: CD orim: fhir:CodeableConcept rdfs:subClassOf dt:CD v2: RXR-4 rim: .doseQuantity
Dosage.doseAndRate
Definition	The amount of medication administered.
Cardinality	0...*
Type	Element
Summary	True
Invariants	ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())`
Mappings	rim: n/a v2: TQ1-2
Dosage.doseAndRate.id
Definition	Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.
Cardinality	0...1
Type
Mappings	rim: n/a
Dosage.doseAndRate.extension
Definition	May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.
Cardinality	0...*
Type	Extension
Alias	extensions, user content
Comments	There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.
Slicing	Unordered, Open, by url(Value)
Invariants	ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` ext-1: Must have either extensions or value[x], not both `extension.exists() != value.exists()`
Mappings	rim: n/a rim: N/A
Dosage.doseAndRate.type
Definition	The kind of dose or rate specified, for example, ordered or calculated.
Cardinality	0...1
Type	CodeableConcept
Binding	The kind of dose or rate specified. DoseAndRateType (example)
Summary	True
Requirements	If the type is not populated, assume to be "ordered".
Comments	Not all terminology uses fit this general pattern. In some cases, models should not use CodeableConcept and use Coding directly and provide their own structure for managing text, codings, translations and the relationship between elements and pre- and post-coordination.
Invariants	ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())`
Mappings	rim: n/a v2: CE/CNE/CWE rim: CD orim: fhir:CodeableConcept rdfs:subClassOf dt:CD v2: RXO-21; RXE-23
Dosage.doseAndRate.dose[x]
Definition	Amount of medication per dose.
Cardinality	0...1
Type	Range
Summary	True
Requirements	The amount of therapeutic or other substance given at one administration event.
Comments	Note that this specifies the quantity of the specified medication, not the quantity for each active ingredient(s). Each ingredient amount can be communicated in the Medication resource. For example, if one wants to communicate that a tablet was 375 mg, where the dose was one tablet, you can use the Medication resource to document that the tablet was comprised of 375 mg of drug XYZ. Alternatively if the dose was 375 mg, then you may only need to use the Medication resource to indicate this was a tablet. If the example were an IV such as dopamine and you wanted to communicate that 400mg of dopamine was mixed in 500 ml of some IV solution, then this would all be communicated in the Medication resource. If the administration is not intended to be instantaneous (rate is present or timing has a duration), this can be specified to convey the total amount to be administered over the period of time as indicated by the schedule e.g. 500 ml in dose, with timing used to convey that this should be done over 4 hours.
Invariants	ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())`
Mappings	rim: n/a v2: RXO-2, RXE-3 rim: .doseQuantity
Dosage.doseAndRate.rate[x]
Definition	Amount of medication per unit of time.
Cardinality	0...1
Type	Ratio
Summary	True
Requirements	Identifies the speed with which the medication was or will be introduced into the patient. Typically the rate for an infusion e.g. 100 ml per 1 hour or 100 ml/hr. May also be expressed as a rate per unit of time e.g. 500 ml per 2 hours. Other examples: 200 mcg/min or 200 mcg/1 minute; 1 liter/8 hours. Sometimes, a rate can imply duration when expressed as total volume / duration (e.g. 500mL/2 hours implies a duration of 2 hours). However, when rate doesn't imply duration (e.g. 250mL/hour), then the timing.repeat.duration is needed to convey the infuse over time period.
Comments	It is possible to supply both a rate and a doseQuantity to provide full details about how the medication is to be administered and supplied. If the rate is intended to change over time, depending on local rules/regulations, each change should be captured as a new version of the MedicationRequest with an updated rate, or captured with a new MedicationRequest with the new rate. It is possible to specify a rate over time (for example, 100 ml/hour) using either the rateRatio and rateQuantity. The rateQuantity approach requires systems to have the capability to parse UCUM grammer where ml/hour is included rather than a specific ratio where the time is specified as the denominator. Where a rate such as 500ml over 2 hours is specified, the use of rateRatio may be more semantically correct than specifying using a rateQuantity of 250 mg/hour.
Invariants	ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())`
Mappings	rim: n/a v2: RXE22, RXE23, RXE-24 rim: .rateQuantity
Dosage.maxDosePerPeriod
Definition	Upper limit on medication per unit of time.
Cardinality	0...1
Type	Ratio
Summary	True
Requirements	The maximum total quantity of a therapeutic substance that may be administered to a subject over the period of time. For example, 1000mg in 24 hours.
Comments	This is intended for use as an adjunct to the dosage when there is an upper cap. For example "2 tablets every 4 hours to a maximum of 8/day".
Invariants	ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` rat-1: Numerator and denominator SHALL both be present, or both are absent. If both are absent, there SHALL be some extension present `(numerator.empty() xor denominator.exists()) and (numerator.exists() or extension.exists())`
Mappings	rim: n/a v2: N/A rim: RTO v2: RXO-23, RXE-19 rim: .maxDoseQuantity
Dosage.maxDosePerAdministration
Definition	Upper limit on medication per administration.
Cardinality	0...1
Type	SimpleQuantity
Summary	True
Requirements	The maximum total quantity of a therapeutic substance that may be administered to a subject per administration.
Comments	This is intended for use as an adjunct to the dosage when there is an upper cap. For example, a body surface area related dose with a maximum amount, such as 1.5 mg/m2 (maximum 2 mg) IV over 5 – 10 minutes would have doseQuantity of 1.5 mg/m2 and maxDosePerAdministration of 2 mg.
Invariants	ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` qty-3: If a code for the unit is present, the system SHALL also be present `code.empty() or system.exists()` sqty-1: The comparator is not used on a SimpleQuantity `comparator.empty()`
Mappings	rim: n/a v2: SN (see also Range) or CQ rim: PQ, IVL<PQ>, MO, CO, depending on the values rim: not supported
Dosage.maxDosePerLifetime
Definition	Upper limit on medication per lifetime of the patient.
Cardinality	0...1
Type	SimpleQuantity
Summary	True
Requirements	The maximum total quantity of a therapeutic substance that may be administered per lifetime of the subject.
Comments	The context of use may frequently define what kind of quantity this is and therefore what kind of units can be used. The context of use may also restrict the values for the comparator.
Invariants	ele-1: All FHIR elements must have a @value or children `hasValue() or (children().count() > id.count())` qty-3: If a code for the unit is present, the system SHALL also be present `code.empty() or system.exists()` sqty-1: The comparator is not used on a SimpleQuantity `comparator.empty()`
Mappings	rim: n/a v2: SN (see also Range) or CQ rim: PQ, IVL<PQ>, MO, CO, depending on the values rim: not supported

Implementation guidance

Implementation guidance follows for each data item within the Dosage structure, in the order in which they are shown in the above treeview.

Element: `sequence`

Multi-sequence dosage instructions.

A multi-sequence would be required where a dosage instruction changes over a given time schedule, where a dosage instruction includes optional follow-up doses or where a concurrent dosage instruction is required for the same medication at a different dose.

Examples below include Prednisolone to treat Bell’s palsy where a dose starts at 60 mg per day for a period of time then reduces by 10 mg per day. This would be described as a sequential dosage instruction. A concurrent dosage example is provided to describe a different dose in the morning to that at midday.

Sequential Instructions

Where the value of sequence is an incremental integer it defines a sequential instruction.

Example use of the FHIR R4 Dosage using multiple sequential sequences

<MedicationRequest xmlns="http://hl7.org/fhir">
    <id value="43955772-3136-49be-829e-ac04b56894d5" />
    <meta>
        <profile value="https://fhir.hl7.org.uk/StructureDefinition/UKCore-MedicationRequest" />
    </meta>
    <status value="active" />
    <intent value="order" />
    <category>
        <coding>
            <system value="http://terminology.hl7.org/CodeSystem/medicationrequest-category" />
            <code value="inpatient" />
            <display value="inpatient" />
        </coding>
    </category>
    <priority value="routine" />
    <medicationCodeableConcept>
        <coding>
            <system value="https://dmd.nhs.uk" />
            <code value="52388000" />
            <display value="Prednisolone" />
        </coding>
    </medicationCodeableConcept>
    <subject>
        <identifier>
            <system value="https://fhir.nhs.uk/Id/nhs-number" />
            <value value="9999999999" />
        </identifier>
    </subject>
    <authoredOn value="2020-05-15T15:00:00Z" />
    <requester>
        <reference value="urn:staff-1112" />
        <display value="Dr Maikeu Well" />
    </requester>
    <recorder>
        <reference value="urn:staff-1112" />
        <display value="Dr Maikeu Well" />
    </recorder>
    <dosageInstruction>
        <sequence value="1" />
        <text value="60 milligram - once a day - for 4 days" />
        <timing>
            <repeat>
                <boundsDuration>
                    <value value="4" />
                    <unit value="day" />
                    <system value="http://unitsofmeasure.org" />
                    <code value="d" />
                </boundsDuration>
                <frequency value="1" />
                <period value="1" />
                <periodUnit value="d" />
            </repeat>
        </timing>
        <doseAndRate>
            <doseQuantity>
                <value value="60" />
                <unit value="milligram" />
                <system value="http://unitsofmeasure.org" />
                <code value="mg" />
            </doseQuantity>
        </doseAndRate>
    </dosageInstruction>
    <dosageInstruction>
        <sequence value="2" />
        <text value="50 milligram - once a day - for 1 day" />
        <timing>
            <repeat>
                <boundsDuration>
                    <value value="1" />
                    <unit value="day" />
                    <system value="http://unitsofmeasure.org" />
                    <code value="d" />
                </boundsDuration>
                <frequency value="1" />
                <period value="1" />
                <periodUnit value="d" />
            </repeat>
        </timing>
        <doseAndRate>
            <doseQuantity>
                <value value="50" />
                <unit value="milligram" />
                <system value="http://unitsofmeasure.org" />
                <code value="mg" />
            </doseQuantity>
        </doseAndRate>
    </dosageInstruction>
    <dosageInstruction>
        <sequence value="3" />
        <text value="40 milligram - once a day - for 1 day" />
        <timing>
            <repeat>
                <boundsDuration>
                    <value value="1" />
                    <unit value="day" />
                    <system value="http://unitsofmeasure.org" />
                    <code value="d" />
                </boundsDuration>
                <frequency value="1" />
                <period value="1" />
                <periodUnit value="d" />
            </repeat>
        </timing>
        <doseAndRate>
            <doseQuantity>
                <value value="40" />
                <unit value="milligram" />
                <system value="http://unitsofmeasure.org" />
                <code value="mg" />
            </doseQuantity>
        </doseAndRate>
    </dosageInstruction>
    <dosageInstruction>
        <sequence value="4" />
        <text value="30 milligram - once a day - for 1 day" />
        <timing>
            <repeat>
                <boundsDuration>
                    <value value="1" />
                    <unit value="day" />
                    <system value="http://unitsofmeasure.org" />
                    <code value="d" />
                </boundsDuration>
                <frequency value="1" />
                <period value="1" />
                <periodUnit value="d" />
            </repeat>
        </timing>
        <doseAndRate>
            <doseQuantity>
                <value value="30" />
                <unit value="milligram" />
                <system value="http://unitsofmeasure.org" />
                <code value="mg" />
            </doseQuantity>
        </doseAndRate>
    </dosageInstruction>
    <dosageInstruction>
        <sequence value="5" />
        <text value="20 milligram - once a day - for 1 day" />
        <timing>
            <repeat>
                <boundsDuration>
                    <value value="1" />
                    <unit value="day" />
                    <system value="http://unitsofmeasure.org" />
                    <code value="d" />
                </boundsDuration>
                <frequency value="1" />
                <period value="1" />
                <periodUnit value="d" />
            </repeat>
        </timing>
        <doseAndRate>
            <doseQuantity>
                <value value="20" />
                <unit value="milligram" />
                <system value="http://unitsofmeasure.org" />
                <code value="mg" />
            </doseQuantity>
        </doseAndRate>
    </dosageInstruction>
    <dosageInstruction>
        <sequence value="6" />
        <text value="10 milligram - once a day - for 1 day - Then stop" />
        <additionalInstruction>
            <coding>
                <system value="http://snomed.info/sct" />
                <code value="422327006" />
                <display value="Then stop" />
            </coding>
        </additionalInstruction>
        <timing>
            <repeat>
                <boundsDuration>
                    <value value="1" />
                    <unit value="day" />
                    <system value="http://unitsofmeasure.org" />
                    <code value="d" />
                </boundsDuration>
                <frequency value="1" />
                <period value="1" />
                <periodUnit value="d" />
            </repeat>
        </timing>
        <doseAndRate>
            <doseQuantity>
                <value value="10" />
                <unit value="milligram" />
                <system value="http://unitsofmeasure.org" />
                <code value="mg" />
            </doseQuantity>
        </doseAndRate>
    </dosageInstruction>
    <substitution>
        <allowedBoolean value="false" />
    </substitution>
</MedicationRequest>

{
    "resourceType": "MedicationRequest",
    "id": "43955772-3136-49be-829e-ac04b56894d5",
    "meta": {
        "profile":  [
            "https://fhir.hl7.org.uk/StructureDefinition/UKCore-MedicationRequest"
        ]
    },
    "status": "active",
    "intent": "order",
    "category":  [
        {
            "coding":  [
                {
                    "system": "http://terminology.hl7.org/CodeSystem/medicationrequest-category",
                    "code": "inpatient",
                    "display": "inpatient"
                }
            ]
        }
    ],
    "priority": "routine",
    "medicationCodeableConcept": {
        "coding":  [
            {
                "system": "https://dmd.nhs.uk",
                "code": "52388000",
                "display": "Prednisolone"
            }
        ]
    },
    "subject": {
        "identifier": {
            "system": "https://fhir.nhs.uk/Id/nhs-number",
            "value": "9999999999"
        }
    },
    "authoredOn": "2020-05-15T15:00:00Z",
    "requester": {
        "reference": "urn:staff-1112",
        "display": "Dr Maikeu Well"
    },
    "recorder": {
        "reference": "urn:staff-1112",
        "display": "Dr Maikeu Well"
    },
    "dosageInstruction":  [
        {
            "sequence": 1,
            "text": "60 milligram - once a day - for 4 days",
            "timing": {
                "repeat": {
                    "boundsDuration": {
                        "value": 4,
                        "unit": "day",
                        "system": "http://unitsofmeasure.org",
                        "code": "d"
                    },
                    "frequency": 1,
                    "period": 1,
                    "periodUnit": "d"
                }
            },
            "doseAndRate":  [
                {
                    "doseQuantity": {
                        "value": 60,
                        "unit": "milligram",
                        "system": "http://unitsofmeasure.org",
                        "code": "mg"
                    }
                }
            ]
        },
        {
            "sequence": 2,
            "text": "50 milligram - once a day - for 1 day",
            "timing": {
                "repeat": {
                    "boundsDuration": {
                        "value": 1,
                        "unit": "day",
                        "system": "http://unitsofmeasure.org",
                        "code": "d"
                    },
                    "frequency": 1,
                    "period": 1,
                    "periodUnit": "d"
                }
            },
            "doseAndRate":  [
                {
                    "doseQuantity": {
                        "value": 50,
                        "unit": "milligram",
                        "system": "http://unitsofmeasure.org",
                        "code": "mg"
                    }
                }
            ]
        },
        {
            "sequence": 3,
            "text": "40 milligram - once a day - for 1 day",
            "timing": {
                "repeat": {
                    "boundsDuration": {
                        "value": 1,
                        "unit": "day",
                        "system": "http://unitsofmeasure.org",
                        "code": "d"
                    },
                    "frequency": 1,
                    "period": 1,
                    "periodUnit": "d"
                }
            },
            "doseAndRate":  [
                {
                    "doseQuantity": {
                        "value": 40,
                        "unit": "milligram",
                        "system": "http://unitsofmeasure.org",
                        "code": "mg"
                    }
                }
            ]
        },
        {
            "sequence": 4,
            "text": "30 milligram - once a day - for 1 day",
            "timing": {
                "repeat": {
                    "boundsDuration": {
                        "value": 1,
                        "unit": "day",
                        "system": "http://unitsofmeasure.org",
                        "code": "d"
                    },
                    "frequency": 1,
                    "period": 1,
                    "periodUnit": "d"
                }
            },
            "doseAndRate":  [
                {
                    "doseQuantity": {
                        "value": 30,
                        "unit": "milligram",
                        "system": "http://unitsofmeasure.org",
                        "code": "mg"
                    }
                }
            ]
        },
        {
            "sequence": 5,
            "text": "20 milligram - once a day - for 1 day",
            "timing": {
                "repeat": {
                    "boundsDuration": {
                        "value": 1,
                        "unit": "day",
                        "system": "http://unitsofmeasure.org",
                        "code": "d"
                    },
                    "frequency": 1,
                    "period": 1,
                    "periodUnit": "d"
                }
            },
            "doseAndRate":  [
                {
                    "doseQuantity": {
                        "value": 20,
                        "unit": "milligram",
                        "system": "http://unitsofmeasure.org",
                        "code": "mg"
                    }
                }
            ]
        },
        {
            "sequence": 6,
            "text": "10 milligram - once a day - for 1 day - Then stop",
            "additionalInstruction":  [
                {
                    "coding":  [
                        {
                            "system": "http://snomed.info/sct",
                            "code": "422327006",
                            "display": "Then stop"
                        }
                    ]
                }
            ],
            "timing": {
                "repeat": {
                    "boundsDuration": {
                        "value": 1,
                        "unit": "day",
                        "system": "http://unitsofmeasure.org",
                        "code": "d"
                    },
                    "frequency": 1,
                    "period": 1,
                    "periodUnit": "d"
                }
            },
            "doseAndRate":  [
                {
                    "doseQuantity": {
                        "value": 10,
                        "unit": "milligram",
                        "system": "http://unitsofmeasure.org",
                        "code": "mg"
                    }
                }
            ]
        }
    ],
    "substitution": {
        "allowedBoolean": false
    }
}

MedicationRequest.id[0]	43955772-3136-49be-829e-ac04b56894d5
MedicationRequest.meta[0].profile[0]	https://fhir.hl7.org.uk/StructureDefinition/UKCore-MedicationRequest
MedicationRequest.status[0]	active
MedicationRequest.intent[0]	order
MedicationRequest.category[0].coding[0].system[0]	http://terminology.hl7.org/CodeSystem/medicationrequest-category
MedicationRequest.category[0].coding[0].code[0]	inpatient
MedicationRequest.category[0].coding[0].display[0]	inpatient
MedicationRequest.priority[0]	routine
MedicationRequest.medication[0].coding[0].system[0]	https://dmd.nhs.uk
MedicationRequest.medication[0].coding[0].code[0]	52388000
MedicationRequest.medication[0].coding[0].display[0]	Prednisolone
MedicationRequest.subject[0].identifier[0].system[0]	https://fhir.nhs.uk/Id/nhs-number
MedicationRequest.subject[0].identifier[0].value[0]	9999999999
MedicationRequest.authoredOn[0]	2020-05-15T15:00:00Z
MedicationRequest.requester[0].reference[0]	urn:staff-1112
MedicationRequest.requester[0].display[0]	Dr Maikeu Well
MedicationRequest.recorder[0].reference[0]	urn:staff-1112
MedicationRequest.recorder[0].display[0]	Dr Maikeu Well
MedicationRequest.dosageInstruction[0].sequence[0]	1
MedicationRequest.dosageInstruction[0].text[0]	60 milligram - once a day - for 4 days
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].bounds[0].value[0]	4
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].bounds[0].unit[0]	day
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].bounds[0].system[0]	http://unitsofmeasure.org
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].bounds[0].code[0]	d
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].frequency[0]	1
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].period[0]	1
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].periodUnit[0]	d
MedicationRequest.dosageInstruction[0].doseAndRate[0].dose[0].value[0]	60
MedicationRequest.dosageInstruction[0].doseAndRate[0].dose[0].unit[0]	milligram
MedicationRequest.dosageInstruction[0].doseAndRate[0].dose[0].system[0]	http://unitsofmeasure.org
MedicationRequest.dosageInstruction[0].doseAndRate[0].dose[0].code[0]	mg
MedicationRequest.dosageInstruction[1].sequence[0]	2
MedicationRequest.dosageInstruction[1].text[0]	50 milligram - once a day - for 1 day
MedicationRequest.dosageInstruction[1].timing[0].repeat[0].bounds[0].value[0]	1
MedicationRequest.dosageInstruction[1].timing[0].repeat[0].bounds[0].unit[0]	day
MedicationRequest.dosageInstruction[1].timing[0].repeat[0].bounds[0].system[0]	http://unitsofmeasure.org
MedicationRequest.dosageInstruction[1].timing[0].repeat[0].bounds[0].code[0]	d
MedicationRequest.dosageInstruction[1].timing[0].repeat[0].frequency[0]	1
MedicationRequest.dosageInstruction[1].timing[0].repeat[0].period[0]	1
MedicationRequest.dosageInstruction[1].timing[0].repeat[0].periodUnit[0]	d
MedicationRequest.dosageInstruction[1].doseAndRate[0].dose[0].value[0]	50
MedicationRequest.dosageInstruction[1].doseAndRate[0].dose[0].unit[0]	milligram
MedicationRequest.dosageInstruction[1].doseAndRate[0].dose[0].system[0]	http://unitsofmeasure.org
MedicationRequest.dosageInstruction[1].doseAndRate[0].dose[0].code[0]	mg
MedicationRequest.dosageInstruction[2].sequence[0]	3
MedicationRequest.dosageInstruction[2].text[0]	40 milligram - once a day - for 1 day
MedicationRequest.dosageInstruction[2].timing[0].repeat[0].bounds[0].value[0]	1
MedicationRequest.dosageInstruction[2].timing[0].repeat[0].bounds[0].unit[0]	day
MedicationRequest.dosageInstruction[2].timing[0].repeat[0].bounds[0].system[0]	http://unitsofmeasure.org
MedicationRequest.dosageInstruction[2].timing[0].repeat[0].bounds[0].code[0]	d
MedicationRequest.dosageInstruction[2].timing[0].repeat[0].frequency[0]	1
MedicationRequest.dosageInstruction[2].timing[0].repeat[0].period[0]	1
MedicationRequest.dosageInstruction[2].timing[0].repeat[0].periodUnit[0]	d
MedicationRequest.dosageInstruction[2].doseAndRate[0].dose[0].value[0]	40
MedicationRequest.dosageInstruction[2].doseAndRate[0].dose[0].unit[0]	milligram
MedicationRequest.dosageInstruction[2].doseAndRate[0].dose[0].system[0]	http://unitsofmeasure.org
MedicationRequest.dosageInstruction[2].doseAndRate[0].dose[0].code[0]	mg
MedicationRequest.dosageInstruction[3].sequence[0]	4
MedicationRequest.dosageInstruction[3].text[0]	30 milligram - once a day - for 1 day
MedicationRequest.dosageInstruction[3].timing[0].repeat[0].bounds[0].value[0]	1
MedicationRequest.dosageInstruction[3].timing[0].repeat[0].bounds[0].unit[0]	day
MedicationRequest.dosageInstruction[3].timing[0].repeat[0].bounds[0].system[0]	http://unitsofmeasure.org
MedicationRequest.dosageInstruction[3].timing[0].repeat[0].bounds[0].code[0]	d
MedicationRequest.dosageInstruction[3].timing[0].repeat[0].frequency[0]	1
MedicationRequest.dosageInstruction[3].timing[0].repeat[0].period[0]	1
MedicationRequest.dosageInstruction[3].timing[0].repeat[0].periodUnit[0]	d
MedicationRequest.dosageInstruction[3].doseAndRate[0].dose[0].value[0]	30
MedicationRequest.dosageInstruction[3].doseAndRate[0].dose[0].unit[0]	milligram
MedicationRequest.dosageInstruction[3].doseAndRate[0].dose[0].system[0]	http://unitsofmeasure.org
MedicationRequest.dosageInstruction[3].doseAndRate[0].dose[0].code[0]	mg
MedicationRequest.dosageInstruction[4].sequence[0]	5
MedicationRequest.dosageInstruction[4].text[0]	20 milligram - once a day - for 1 day
MedicationRequest.dosageInstruction[4].timing[0].repeat[0].bounds[0].value[0]	1
MedicationRequest.dosageInstruction[4].timing[0].repeat[0].bounds[0].unit[0]	day
MedicationRequest.dosageInstruction[4].timing[0].repeat[0].bounds[0].system[0]	http://unitsofmeasure.org
MedicationRequest.dosageInstruction[4].timing[0].repeat[0].bounds[0].code[0]	d
MedicationRequest.dosageInstruction[4].timing[0].repeat[0].frequency[0]	1
MedicationRequest.dosageInstruction[4].timing[0].repeat[0].period[0]	1
MedicationRequest.dosageInstruction[4].timing[0].repeat[0].periodUnit[0]	d
MedicationRequest.dosageInstruction[4].doseAndRate[0].dose[0].value[0]	20
MedicationRequest.dosageInstruction[4].doseAndRate[0].dose[0].unit[0]	milligram
MedicationRequest.dosageInstruction[4].doseAndRate[0].dose[0].system[0]	http://unitsofmeasure.org
MedicationRequest.dosageInstruction[4].doseAndRate[0].dose[0].code[0]	mg
MedicationRequest.dosageInstruction[5].sequence[0]	6
MedicationRequest.dosageInstruction[5].text[0]	10 milligram - once a day - for 1 day - Then stop
MedicationRequest.dosageInstruction[5].additionalInstruction[0].coding[0].system[0]	http://snomed.info/sct
MedicationRequest.dosageInstruction[5].additionalInstruction[0].coding[0].code[0]	422327006
MedicationRequest.dosageInstruction[5].additionalInstruction[0].coding[0].display[0]	Then stop
MedicationRequest.dosageInstruction[5].timing[0].repeat[0].bounds[0].value[0]	1
MedicationRequest.dosageInstruction[5].timing[0].repeat[0].bounds[0].unit[0]	day
MedicationRequest.dosageInstruction[5].timing[0].repeat[0].bounds[0].system[0]	http://unitsofmeasure.org
MedicationRequest.dosageInstruction[5].timing[0].repeat[0].bounds[0].code[0]	d
MedicationRequest.dosageInstruction[5].timing[0].repeat[0].frequency[0]	1
MedicationRequest.dosageInstruction[5].timing[0].repeat[0].period[0]	1
MedicationRequest.dosageInstruction[5].timing[0].repeat[0].periodUnit[0]	d
MedicationRequest.dosageInstruction[5].doseAndRate[0].dose[0].value[0]	10
MedicationRequest.dosageInstruction[5].doseAndRate[0].dose[0].unit[0]	milligram
MedicationRequest.dosageInstruction[5].doseAndRate[0].dose[0].system[0]	http://unitsofmeasure.org
MedicationRequest.dosageInstruction[5].doseAndRate[0].dose[0].code[0]	mg
MedicationRequest.substitution[0].allowed[0]	False

MedicationRequest

id : 43955772-3136-49be-829e-ac04b56894d5

meta

profile : https://fhir.hl7.org.uk/StructureDefinition/UKCore-MedicationRequest

status : active

intent : order

category

coding

system : http://terminology.hl7.org/CodeSystem/medicationrequest-category

code : inpatient

display : inpatient

priority : routine

medication

coding

system : https://dmd.nhs.uk

code : 52388000

display : Prednisolone

subject

identifier

system : https://fhir.nhs.uk/Id/nhs-number

value : 9999999999

authoredOn : 2020-05-15T15:00:00Z

requester

reference : urn:staff-1112

display : Dr Maikeu Well

recorder

reference : urn:staff-1112

display : Dr Maikeu Well

dosageInstruction

sequence : 1

text : 60 milligram - once a day - for 4 days

timing

repeat

bounds

value : 4

unit : day

system : http://unitsofmeasure.org

code : d

frequency : 1

period : 1

periodUnit : d

doseAndRate

dose

value : 60

unit : milligram

system : http://unitsofmeasure.org

code : mg

dosageInstruction

sequence : 2

text : 50 milligram - once a day - for 1 day

timing

repeat

bounds

value : 1

unit : day

system : http://unitsofmeasure.org

code : d

frequency : 1

period : 1

periodUnit : d

doseAndRate

dose

value : 50

unit : milligram

system : http://unitsofmeasure.org

code : mg

dosageInstruction

sequence : 3

text : 40 milligram - once a day - for 1 day

timing

repeat

bounds

value : 1

unit : day

system : http://unitsofmeasure.org

code : d

frequency : 1

period : 1

periodUnit : d

doseAndRate

dose

value : 40

unit : milligram

system : http://unitsofmeasure.org

code : mg

dosageInstruction

sequence : 4

text : 30 milligram - once a day - for 1 day

timing

repeat

bounds

value : 1

unit : day

system : http://unitsofmeasure.org

code : d

frequency : 1

period : 1

periodUnit : d

doseAndRate

dose

value : 30

unit : milligram

system : http://unitsofmeasure.org

code : mg

dosageInstruction

sequence : 5

text : 20 milligram - once a day - for 1 day

timing

repeat

bounds

value : 1

unit : day

system : http://unitsofmeasure.org

code : d

frequency : 1

period : 1

periodUnit : d

doseAndRate

dose

value : 20

unit : milligram

system : http://unitsofmeasure.org

code : mg

dosageInstruction

sequence : 6

text : 10 milligram - once a day - for 1 day - Then stop

additionalInstruction

coding

system : http://snomed.info/sct

code : 422327006

display : Then stop

timing

repeat

bounds

value : 1

unit : day

system : http://unitsofmeasure.org

code : d

frequency : 1

period : 1

periodUnit : d

doseAndRate

dose

value : 10

unit : milligram

system : http://unitsofmeasure.org

code : mg

substitution

allowed : False

Concurrent Instructions

Where the same integer value of sequence is defines it means a concurrent instruction.

<MedicationRequest xmlns="http://hl7.org/fhir">
    <id value="79159c4f-13c4-457a-8962-67fa22432c15" />
    <meta>
        <profile value="https://fhir.hl7.org.uk/StructureDefinition/UKCore-MedicationRequest" />
    </meta>
    <status value="active" />
    <intent value="order" />
    <category>
        <coding>
            <system value="http://terminology.hl7.org/CodeSystem/medicationrequest-category" />
            <code value="inpatient" />
            <display value="inpatient" />
        </coding>
    </category>
    <priority value="routine" />
    <medicationCodeableConcept>
        <coding>
            <system value="https://dmd.nhs.uk" />
            <code value="317972000" />
            <display value="Furosemide 40mg tablets" />
        </coding>
    </medicationCodeableConcept>
    <subject>
        <identifier>
            <system value="https://fhir.nhs.uk/Id/nhs-number" />
            <value value="9999999999" />
        </identifier>
    </subject>
    <authoredOn value="2020-05-15T15:00:00Z" />
    <requester>
        <reference value="urn:staff-1112" />
        <display value="Dr Maikeu Well" />
    </requester>
    <recorder>
        <reference value="urn:staff-1112" />
        <display value="Dr Maikeu Well" />
    </recorder>
    <dosageInstruction>
        <sequence value="1" />
        <text value="2 tablet - daily - at 08:00 - for 1 week" />
        <timing>
            <repeat>
                <boundsDuration>
                    <value value="1" />
                    <unit value="week" />
                    <system value="http://unitsofmeasure.org" />
                    <code value="wk" />
                </boundsDuration>
                <period value="1" />
                <periodUnit value="d" />
                <timeOfDay value="08:00:00" />
            </repeat>
        </timing>
        <doseAndRate>
            <doseQuantity>
                <value value="2" />
                <unit value="tablet" />
                <system value="http://snomed.info/sct" />
                <code value="428673006" />
            </doseQuantity>
        </doseAndRate>
    </dosageInstruction>
    <dosageInstruction>
        <sequence value="1" />
        <text value="1 tablet - daily - at 12:00 - for 1 week" />
        <timing>
            <repeat>
                <boundsDuration>
                    <value value="1" />
                    <unit value="week" />
                    <system value="http://unitsofmeasure.org" />
                    <code value="wk" />
                </boundsDuration>
                <period value="1" />
                <periodUnit value="d" />
                <timeOfDay value="12:00:00" />
            </repeat>
        </timing>
        <doseAndRate>
            <doseQuantity>
                <value value="1" />
                <unit value="tablet" />
                <system value="http://snomed.info/sct" />
                <code value="428673006" />
            </doseQuantity>
        </doseAndRate>
    </dosageInstruction>
    <substitution>
        <allowedBoolean value="false" />
    </substitution>
</MedicationRequest>

{
    "resourceType": "MedicationRequest",
    "id": "79159c4f-13c4-457a-8962-67fa22432c15",
    "meta": {
        "profile":  [
            "https://fhir.hl7.org.uk/StructureDefinition/UKCore-MedicationRequest"
        ]
    },
    "status": "active",
    "intent": "order",
    "category":  [
        {
            "coding":  [
                {
                    "system": "http://terminology.hl7.org/CodeSystem/medicationrequest-category",
                    "code": "inpatient",
                    "display": "inpatient"
                }
            ]
        }
    ],
    "priority": "routine",
    "medicationCodeableConcept": {
        "coding":  [
            {
                "system": "https://dmd.nhs.uk",
                "code": "317972000",
                "display": "Furosemide 40mg tablets"
            }
        ]
    },
    "subject": {
        "identifier": {
            "system": "https://fhir.nhs.uk/Id/nhs-number",
            "value": "9999999999"
        }
    },
    "authoredOn": "2020-05-15T15:00:00Z",
    "requester": {
        "reference": "urn:staff-1112",
        "display": "Dr Maikeu Well"
    },
    "recorder": {
        "reference": "urn:staff-1112",
        "display": "Dr Maikeu Well"
    },
    "dosageInstruction":  [
        {
            "sequence": 1,
            "text": "2 tablet - daily - at 08:00 - for 1 week",
            "timing": {
                "repeat": {
                    "boundsDuration": {
                        "value": 1,
                        "unit": "week",
                        "system": "http://unitsofmeasure.org",
                        "code": "wk"
                    },
                    "period": 1,
                    "periodUnit": "d",
                    "timeOfDay":  [
                        "08:00:00"
                    ]
                }
            },
            "doseAndRate":  [
                {
                    "doseQuantity": {
                        "value": 2,
                        "unit": "tablet",
                        "system": "http://snomed.info/sct",
                        "code": "428673006"
                    }
                }
            ]
        },
        {
            "sequence": 1,
            "text": "1 tablet - daily - at 12:00 - for 1 week",
            "timing": {
                "repeat": {
                    "boundsDuration": {
                        "value": 1,
                        "unit": "week",
                        "system": "http://unitsofmeasure.org",
                        "code": "wk"
                    },
                    "period": 1,
                    "periodUnit": "d",
                    "timeOfDay":  [
                        "12:00:00"
                    ]
                }
            },
            "doseAndRate":  [
                {
                    "doseQuantity": {
                        "value": 1,
                        "unit": "tablet",
                        "system": "http://snomed.info/sct",
                        "code": "428673006"
                    }
                }
            ]
        }
    ],
    "substitution": {
        "allowedBoolean": false
    }
}

MedicationRequest.id[0]	79159c4f-13c4-457a-8962-67fa22432c15
MedicationRequest.meta[0].profile[0]	https://fhir.hl7.org.uk/StructureDefinition/UKCore-MedicationRequest
MedicationRequest.status[0]	active
MedicationRequest.intent[0]	order
MedicationRequest.category[0].coding[0].system[0]	http://terminology.hl7.org/CodeSystem/medicationrequest-category
MedicationRequest.category[0].coding[0].code[0]	inpatient
MedicationRequest.category[0].coding[0].display[0]	inpatient
MedicationRequest.priority[0]	routine
MedicationRequest.medication[0].coding[0].system[0]	https://dmd.nhs.uk
MedicationRequest.medication[0].coding[0].code[0]	317972000
MedicationRequest.medication[0].coding[0].display[0]	Furosemide 40mg tablets
MedicationRequest.subject[0].identifier[0].system[0]	https://fhir.nhs.uk/Id/nhs-number
MedicationRequest.subject[0].identifier[0].value[0]	9999999999
MedicationRequest.authoredOn[0]	2020-05-15T15:00:00Z
MedicationRequest.requester[0].reference[0]	urn:staff-1112
MedicationRequest.requester[0].display[0]	Dr Maikeu Well
MedicationRequest.recorder[0].reference[0]	urn:staff-1112
MedicationRequest.recorder[0].display[0]	Dr Maikeu Well
MedicationRequest.dosageInstruction[0].sequence[0]	1
MedicationRequest.dosageInstruction[0].text[0]	2 tablet - daily - at 08:00 - for 1 week
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].bounds[0].value[0]	1
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].bounds[0].unit[0]	week
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].bounds[0].system[0]	http://unitsofmeasure.org
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].bounds[0].code[0]	wk
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].period[0]	1
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].periodUnit[0]	d
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].timeOfDay[0]	08:00:00
MedicationRequest.dosageInstruction[0].doseAndRate[0].dose[0].value[0]	2
MedicationRequest.dosageInstruction[0].doseAndRate[0].dose[0].unit[0]	tablet
MedicationRequest.dosageInstruction[0].doseAndRate[0].dose[0].system[0]	http://snomed.info/sct
MedicationRequest.dosageInstruction[0].doseAndRate[0].dose[0].code[0]	428673006
MedicationRequest.dosageInstruction[1].sequence[0]	1
MedicationRequest.dosageInstruction[1].text[0]	1 tablet - daily - at 12:00 - for 1 week
MedicationRequest.dosageInstruction[1].timing[0].repeat[0].bounds[0].value[0]	1
MedicationRequest.dosageInstruction[1].timing[0].repeat[0].bounds[0].unit[0]	week
MedicationRequest.dosageInstruction[1].timing[0].repeat[0].bounds[0].system[0]	http://unitsofmeasure.org
MedicationRequest.dosageInstruction[1].timing[0].repeat[0].bounds[0].code[0]	wk
MedicationRequest.dosageInstruction[1].timing[0].repeat[0].period[0]	1
MedicationRequest.dosageInstruction[1].timing[0].repeat[0].periodUnit[0]	d
MedicationRequest.dosageInstruction[1].timing[0].repeat[0].timeOfDay[0]	12:00:00
MedicationRequest.dosageInstruction[1].doseAndRate[0].dose[0].value[0]	1
MedicationRequest.dosageInstruction[1].doseAndRate[0].dose[0].unit[0]	tablet
MedicationRequest.dosageInstruction[1].doseAndRate[0].dose[0].system[0]	http://snomed.info/sct
MedicationRequest.dosageInstruction[1].doseAndRate[0].dose[0].code[0]	428673006
MedicationRequest.substitution[0].allowed[0]	False

MedicationRequest

id : 79159c4f-13c4-457a-8962-67fa22432c15

meta

profile : https://fhir.hl7.org.uk/StructureDefinition/UKCore-MedicationRequest

status : active

intent : order

category

coding

system : http://terminology.hl7.org/CodeSystem/medicationrequest-category

code : inpatient

display : inpatient

priority : routine

medication

coding

system : https://dmd.nhs.uk

code : 317972000

display : Furosemide 40mg tablets

subject

identifier

system : https://fhir.nhs.uk/Id/nhs-number

value : 9999999999

authoredOn : 2020-05-15T15:00:00Z

requester

reference : urn:staff-1112

display : Dr Maikeu Well

recorder

reference : urn:staff-1112

display : Dr Maikeu Well

dosageInstruction

sequence : 1

text : 2 tablet - daily - at 08:00 - for 1 week

timing

repeat

bounds

value : 1

unit : week

system : http://unitsofmeasure.org

code : wk

period : 1

periodUnit : d

timeOfDay : 08:00:00

doseAndRate

dose

value : 2

unit : tablet

system : http://snomed.info/sct

code : 428673006

dosageInstruction

sequence : 1

text : 1 tablet - daily - at 12:00 - for 1 week

timing

repeat

bounds

value : 1

unit : week

system : http://unitsofmeasure.org

code : wk

period : 1

periodUnit : d

timeOfDay : 12:00:00

doseAndRate

dose

value : 1

unit : tablet

system : http://snomed.info/sct

code : 428673006

substitution

allowed : False

Element: `text`

IMPORTANT: This guidance differs from the international FHIR specification. The FHIR standard is ambiguous with contradictory statements for what may or may not be contained within the text element.

Recommendation: We recommend text is populated with a textual representation of the complete dosage instruction, in terms understood by a healthcare professional, excluding;

Name or description of the medication (Note 1)

Problem or condition to which the medicine relates (Note 2)

Any patientInstruction string (Note 3)

This approach allows the text to be safely used by clinical systems that cannot (yet) consume the complete FHIR Dosage structure. All dosing instructions within text should also be contained within the relevant structured elements of the FHIR Dosage to allow the clinical system to consume the FHIR Dosage without requiring the human user to interpret the contents of text.

Note 1: The name or description of the medication is conveyed as a codeableConcept or referenced Medication resource in the resource that contains the Dosage structure.

Note 2: The reason for medication is conveyed within the reasonCode or reasonReference within the MedicationRequest and MedicationStatement resources.

Note 3: The patientInstruction element contains equivalent information to text but in terms that are understood by the patient or consumer so should not be repeated within text.

Exception: EPS FHIR Facade Implementation
An exception to note 2 above relates to the current implementation of the Electronic Prescription Service - FHIR API. The text may be appended with the reason for the medication (indication). The current implementation of the EPS converts the FHIR payload to HL7v3 for backwards compatibility. Wthin the HL7v3 data model, there is nowhere to hold the indication other than as an appendment to the free-text dosage instruction.

The textual representation must align with what the clinical user selects or sees on-screen. A textual and clinical equivalent of every element within the Dosage structure, excluding text, must be contained within text, with the exception of any patientInstruction string.

This approach allows clinically safe dosage interoperability between systems that do and do not support the full Dosage structure. A consumer system that can only handle a dosage text string will consume text and ignore all other elements of the Dosage structure. A provider system that can only handle a dosage text string will only populate the text element of the Dosage structure.

The approach we recommend allows a fully FHIR-compliant consumer system to process all elements of Dosage excluding text. A system that only supports text-based dosage instructions will process only text for clinical users or patientInstruction for the patient user. Both implementations will consume an equivalent dosage instruction, albiet one as text and one that is machine readable.

Implementation Example A

A provider system allows the user to pick an order sentence, e.g. “Two tablet(s), two times a day, with food. Please do not chew the tablets”. This string goes into text and in the background, the provider system constructs the coded Dosage structure.

<dosageInstruction>
     <text value="Two tablet(s), two times a day, with food. Please do not chew the tablets" />
     <timing>
          <repeat>
              <frequency value="2" />
              <period value="1" />
              <periodUnit value="d" />
              <when value="C"/>
          </repeat>
     </timing>
     <doseAndRate>
          <doseQuantity>
              <value value="2" />
              <unit value="tablet" />
              <system value="http://snomed.info/sct" />
              <code value="428673006" />
          </doseQuantity>
     </doseAndRate>
     <additionalInstruction>
         <text value=”Please do not chew the tablets” />
     </additionalInstruction>
</dosageInstruction>

Implementation Example B

A provider system allows the user to construct a dosage instruction using various user interface components. The system translatesAd the coded information into a text string for text. Refer to our translation algorithm for guidance for such a translation. In the background, the provider system constructs the coded Dosage structure.

<dosageInstruction>
     <text value="2 tablets - twice a day – at a meal - Please do not chew the tablets" />
     <timing>
          <repeat>
              <frequency value="2" />
              <period value="1" />
              <periodUnit value="d" />
              <when value="C"/>
          </repeat>
     </timing>
     <doseAndRate>
          <doseQuantity>
              <value value="2" />
              <unit value="tablet" />
              <system value="http://snomed.info/sct" />
              <code value="428673006" />
          </doseQuantity>
     </doseAndRate>
     <additionalInstruction>
         <text value=”Please do not chew the tablets” />
     </additionalInstruction>
</dosageInstruction>

Element: `additionalInstruction`

Additional dosage instructions that can be either SNOMED-CT coded terms or free-text instructions.

Where suitable SNOMED-CT coded terms exist, use them instead of free-text instructions. See the SNOMED-CT hierarchy descendants of 419492006 Additional dosage instructions (qualifier value). These terms are also available from the example FHIR valueset binding.

Note: Where no code exists, additionalInstructions can be conveyed as free-text; however, if free-text is used rather than a SNOMED-CT coded term, the `MedicationRequest` cannot be computable, and requires human intervention in the case of conditional or contradictory instructions.

Coded instruction

<additionalInstruction>
    <coding> 
        <system value="http://snomed.info/sct"/> 
        <code value="419529008"/> 
        <display value="Dissolved under the tongue "/> 
    </coding>
</additionalInstruction>

Multiple coded instructions

<additionalInstruction>
    <coding> 
        <system value="http://snomed.info/sct"/> 
        <code value="417995008"/> 
        <display value="Dissolve or mix with water before taking"/> 
    </coding>
</additionalInstruction>
<additionalInstruction>
    <coding> 
        <system value="http://snomed.info/sct"/> 
        <code value="417980006"/> 
        <display value="Contains aspirin"/> 
    </coding>
</additionalInstruction>

Free-text instruction

<additionalInstruction>
    <text value="with dialysis"/>
</additionalInstruction>

Note: Where a dosage is expressed as a number of sequence elements and the same additionalInstructions applies to each sequence, then repeat the additionalInstructions within each sequence.

For example:

<dosageInstruction>
    <sequence value="1" />
    <text value="1 tablet - once a day - for 1 week - take with food" />
    <timing>
        <repeat>
            <boundsDuration>
                <value value="1" />
                <unit value="week" />
                <system value="http://unitsofmeasure.org" />
                <code value="wk" />
            </boundsDuration>
            <frequency value="1" />
            <period value="1" />
            <periodUnit value="d" />
        </repeat>
    </timing>
    <doseAndRate>
        <doseQuantity>
            <value value="1" />
            <unit value="tablet" />
            <system value="http://snomed.info/sct" />
            <code value="428673006" />
        </doseQuantity>
    </doseAndRate>
    <additionalInstruction>
        <text value="take with food"/>
    </additionalInstruction>
</dosageInstruction>
<dosageInstruction>
    <sequence value="2" />
    <text value="2 tablets - twice a day - take with food" />
    <timing>
        <repeat>
            <frequency value="2" />
            <period value="1" />
            <periodUnit value="d" />
        </repeat>
    </timing>
    <doseAndRate>
        <doseQuantity>
            <value value="2" />
            <unit value="tablet" />
            <system value="http://snomed.info/sct" />
            <code value="428673006" />
        </doseQuantity>
    </doseAndRate>
    <additionalInstruction>
        <text value="take with food"/>
    </additionalInstruction>
</dosageInstruction>

`additionalInstruction` / `when` overlap

Note: The value-sets for Timing.when and Dosage.additionalInstruction do contain some overlapping values.

For example, they can both describe “with or after food”.

In such cases, use Timing.when instead of a coded Dosage.additionalInstruction.

continue / stop instructions

There may be the need for a clinician to give explicit instructions to either stop or continue taking medication. This could be applicable for discharge medication where one medicine may be for short term pain relief and should be stopped after the prescribed quantity has been taken, while another medicine must be continued until further notice.

The patient’s GP would be informed of this as part of the discharge letter but having these instructions explicitly coded provides a more robust solution.

Three SNOMED-CT codes exist that can be used for this purpose.

“Then stop” (SNOMED concept identifier = 422327006)
“Then discontinue” (SNOMED concept identifier = 421484000)
“Do not stop taking this medicine except on your doctor’s advice” (SNOMED concept identifier = 419444006)

Note: It is recognised that such coded terms are akin to timing instructions so may be more logically containing within the various Dosage.timing structures. These do not currently support coded concept terms. Implementation experience will provide evidence to support any future change to the underlying FHIR specification.

as directed

The use of a dosage instruction akin to “as directed” should be avoided wherever possible; however, if required then this can be SNOMED coded using 421769005 Follow directions (qualifier value) or conveyed as text as a patient instruction.

Element: `patientInstruction`

FHIR defines as "Instructions in terms that are understood by the patient or consumer".

It is good practice that this element contains the complete dosage instruction as a text string, in terms that are understood by the patient or consumer. This includes those prescriptions that the patient may not see or will not self administer, for example, during inpatient care.

There may be occurrences when dosage instructions are designed to be administered only by a healthcare professionals (e.g. IV dosage). In these instances the patientInstruction may be omitted.

It would be expected that in many cases patientInstruction will contain the same dose string as text. The benefit of this element is when different dosage phrasing is required for the clinician and the patient.

<patientInstruction value="2 tablet - 4 times a day - at a meal - Dissolve or mix with water before taking - up to a maximum of 12 tablets in 24 hours"/>

If omitted, patient-facing use cases should present the string representation of the completed dosage as defined within text.

Note: The patientInstruction element is not intended to provide instructions for a medication dispensing label.

Timing Elements: `duration`, `bounds` and `count`

Adding constraints, bounds or limits to a dosage instruction.

Sub-elements: `duration` and `durationMax`

A dosage instruction to be administered over a period of time is defined by a duration and / or a durationMax. These relate to the duration of a single administration so would be applicable for an infusion or potentially a transdermal patch.

The FHIR specification states that if there is a durationMax, there must be a duration.

The use of duration does not apply to medicines that are swallowed or otherwise instantly administered.

over 8 hours

<timing>
	<repeat>
		<duration value="8"/>
		<durationUnit value="h" />
	</repeat>
</timing>

over 10 to 15 minutes

<timing>
	<repeat>
		<duration value="10"/>
		<durationMax value="15"/>
		<durationUnit value="min"/>
	</repeat>
</timing>

Sub-element: `boundsDuration`

An instruction to limit a single course of medication uses the bounds structure. This can be implemented in three ways;

boundsDuration - a period of time, for example: for 7 days
boundsRange - a low / high quantity, for example: for 2 to 3 weeks
boundsPeriod - a date / time start to end period, for example: from 22/02/2021 to 04/03/2021

for 7 days

<timing>
	<repeat>
		<boundsDuration>
			<value value="7"/>
			<unit value="day"/> 
			<system value="http://unitsofmeasure.org"/>
			<code value="d"/>
		</boundsDuration>

	</repeat>
</timing>

for 2 to 3 weeks

<timing> 
	<repeat>
		<boundsRange>
			<low>
				<value value="2"/>
				<unit value="week"/> 
				<system value="http://unitsofmeasure.org"/>
				<code value="wk"/>
			</low>
			<high>
				<value value="3"/>
				<unit value="week"/>
				<system value="http://unitsofmeasure.org"/>
				<code value="wk"/>
			</high>
		</boundsRange>
	</repeat>
</timing>

from 22/02/2021 to 04/03/2021

<timing>  
	<repeat>
        <boundsPeriod>
            <start value="2021-02-22"/>
            <end value="2021-03-04"/>
        </boundsPeriod>
	</repeat>	
</timing>

at least 2 weeks

<timing> 
	<repeat>
		<boundsRange>
			<low>
				<value value="2"/>
				<unit value="week"/> 
				<system value="http://unitsofmeasure.org"/>
				<code value="wk"/>
			</low>
		</boundsRange>
	</repeat>
</timing>

Sub-elements: `count` and `countMax`

Note: Use count and countMax with caution as there are other elements within the Dosage structure that will often be more appropriate.

An instruction for a set number of doses, including the use case of “once”, plus also any maximum number of doses, is defined by count and countMax.

Whilst the count is within repeat it does not mean repeat a number of additional times.

A count of 1 means adminster a dose once.
A count of 3 means administer 3 doses.

The FHIR specification states if there is a countMax, there must be a count.

take once

<timing>
	<repeat>
		<count value="1"/>
	</repeat>
</timing>

take twice

<timing>
	<repeat>
		<count value="2"/>
	</repeat>
</timing>

take three times

Clincal Example: Teicoplanin - 10 mg/kg - every 12 hours - for 3 doses, then 6 to 10 mg/kg - daily

<timing>
	<repeat>
		<count value="3"/>
	</repeat>
</timing>

take three to five times

<timing>
	<repeat>
		<count value="3"/>
		<countMax value="5"/>
	</repeat>
</timing>

Alternatives: Examples where alternatives to using count within a Dosage instruction would be more appropriate.

take once

Instead of using <count value="1"/> use <frequency value="1"/>.

an oral solid - 2 tablets - twice a day - take 14 times

Using a <count value="14"/> is confusing. Is this "take 2 tablets twice a day for 14 days" or "take 2 tablets twice a day and take 14 tablets in total, hence for 7 days"? It would be better to express as a duration.

<duration value="7"/>
<durationUnit value="d" />

Timing Elements: `when`, `offset`, `dayOfWeek`, `timeOfDay`, `event` and `code`

A dosage instruction can be tied to the specific days, dates and times, plus life events related to eating or sleeping.

Sub-elements: `when` and `offset`

The when element ties to the regular life events of sleeping and eating, for example:

C = event occurs at a meal
WAKE = event occurs [offset] after waking

An offset allows the event to be tied x minutes before or after.

The offset is an unsigned integer value so different codes within the when value-set are used to define before or after.

Note: Guidance for the use of timing codes for event occurs before/at/after a meal is currently under review and may be subject to change.

Event occurs at breakfast

<timing>
    <repeat>
        <when value="CM"/>
    </repeat>
</timing>

Event occurs at 1 hour before breakfast

<timing>
    <repeat>
        <when value="ACM"/>
        <offset value="60" />
    </repeat>
</timing>

Event occurs at 1 hour after breakfast

<timing>
    <repeat>
        <when value="PCM"/>
        <offset value="60" />
    </repeat>
</timing>

Sub-elements: `dayOfWeek` and `timeOfDay`

A dosage instruction can specify days of a week and/or specific times within a day for administration.

on Monday and Thursday at 09:00 and 15:00

<timing>
    <repeat>
        <dayOfWeek value="mon" />
        <dayOfWeek value="thu" />
        <timeOfDay value="09:00:00" />
        <timeOfDay value="15:00:00" />
    </repeat>
</timing>

FHIR Inconsistency: The FHIR R4 standard includes a comment that the elements frequency, period and when cannot be used with dayOfWeek and/or timeOfDay. However the rule defined in FHIR R4 only applies to when plus an example exists in the FHIR standard for "Daily at 10:00". Within FHIR R5, the comment has been amended to only apply to when. This guidance is based on the rules defined in FHIR R4 and latest ballot release of FHIR R5.

Daily at 10:00

<timing>
    <repeat>
        <frequency value="1"/>
        <period value="1"/>
        <periodUnit value="d"/>
        <timeOfDay value="10:00:00" />  
    </repeat>
</timing>

Sub-element: `event`

A dosage instruction can specify specific dates and times for administration.

on 1st Nov 2019

<timing>
    <event value="2019-11-01" />
</timing>

on 1st Nov 2019 at 10:30 and again on 1st Dec 2019 at 22:30

<timing>
    <event value="2019-11-01T10:30" />
    <event value="2019-12-01T22:30" />
</timing>

Sub-element: `code`

Allows a code, often a Latin abbreviation, for a timing schedule to be specified, for example: BID = twice a day

Note: It is recommended that such codes are not used when the rest of the Dosage structure is supported by the system. Use the structures like frequency and period instead, so that a timing schedule can be computable.

Timing Elements: `frequency` and `period`

A large proportion of cases, especially those where the medication are described using a VMP or AMP concept, can have a dosage instruction defined with a combination of frequency and period elements within the Timing structure.

Simple dosage timing instructions can be described using frequency and period.

The combination of frequency and period allows for the two commonly used expressions of:

x times a period
every x period

The unit of the period must be one of the UCUM units:

UCUM Unit	Definition
`s`	second
`min`	minute
`h`	hour
`d`	day
`wk`	week
`mo`	month
`a`	year

A frequencyMax and/or periodMax can also be used to define ranges. The FHIR specification states if there's a periodMax, there must be a period.

Every 8 hours

<timing>
    <repeat>
        <frequency value="1"/>
        <period value="8"/>
        <periodUnit value="h"/>
    </repeat>
</timing>

4 times a day

<timing>
    <repeat>
        <frequency value="4"/>
        <period value="1"/>
        <periodUnit value="d"/>
    </repeat>
</timing>

2 to 4 times a day

<timing>
    <repeat>
        <frequency value="2"/>
        <frequencyMax value="4"/>
        <period value="1"/>
        <periodUnit value="d"/>
    </repeat>
</timing>

up to 4 times a day

<timing>
    <repeat>
        <frequencyMax value="4"/>
        <period value="1"/>
        <periodUnit value="d"/>
    </repeat>
</timing>

every 3 to 4 weeks

<timing>
    <repeat>
        <frequency value="1"/>
        <period value="3"/>
        <periodMax value="4"/>
        <periodUnit value="wk"/>
    </repeat>
</timing>

3 to 4 times every 1 to 2 weeks

<timing>
    <repeat>
        <frequency value="3"/>
        <frequencyMax value="4"/>
        <period value="1"/>
        <periodMax value="2"/>
        <periodUnit value="wk"/>
    </repeat>
</timing>

daily

<timing>
    <repeat>
        <frequency value="1"/>
        <period value="1"/>
        <periodUnit value="d"/>
    </repeat>
</timing>

twice a week

<timing>
    <repeat>
        <frequency value="2"/>
        <period value="1"/>
        <periodUnit value="wk"/>
    </repeat>
</timing>

Examples of potentially confusing timing instructions

When converting the information into a FHIR message to a human readable version the frequency could be misconstrued.

For example:

take twice a week on a Monday and Thursday

Is the patient being instructed to take the medication twice per day on a Monday and Thursday (4 individual doses), or twice per week on a Monday and Thursday (2 individual doses)?

Bad ambiguious example:
on Monday and Thursday - take twice

<timing>
    <repeat>
        <count value="2" />
        <dayOfWeek value="mon" />
        <dayOfWeek value="thu" />
    </repeat>
</timing>

Using the dose-to-text guidance within this documentation the above would be displayed as:

on Monday and Thursday - take twice

Better specific example:
twice a week - on Monday and Thursday

<timing>
    <repeat>
        <frequency value="2"/>
        <period value="1" />
        <periodUnit value="wk"/>
        <dayOfWeek value="mon" />
        <dayOfWeek value="thu" />
    </repeat>
</timing>

Using the dose-to-text guidance within this documentation the above would be displayed as:

twice a week - on Monday and Thursday

Alternative better specific example:
on Monday and Thursday

<timing>
    <repeat>
        <dayOfWeek value="mon" />
        <dayOfWeek value="thu" />
    </repeat>
</timing>

Using the dose-to-text guidance within this documentation the above would be displayed as:

on Monday and Thursday

Real-World Example

This prescription is used for immunocompromised patients to provide prophylaxis against a particular strain of pneumonia.

Co-trimoxazole 80mg/400mg tablets (Actavis UK Ltd) - 1 tablet - twice a day - on Monday, Wednesday and Friday.

Element: `asNeeded`

Dosing 'asNeeded' and 'asNeededCodeableConcept' instructions.

Sub-element: `Dosage.asNeeded[x]`

The asNeeded structure can be used to define a simple “as required” (or “pro re nata” expressed as “PRN” for those who still prefer to use Latin abbreviations) instructions.

In this case use the asNeededBoolean option. The absence of asNeededBoolean is equivalent to where asNeededBoolean has a value of false.

The asNeededCodeableConcept option is used to bound the dosage instruction to a coded term. Any number of coded terms can be used from the SNOMED-CT hierarchy as a descendant of 404684003 Clinical Finding (finding). An extensive medication-as-needed-reason value-set is defined within FHIR which is a subset of the SNOMED-CT clinical findings hierarchy.

Example #1: Dosage.asNeeded

<MedicationRequest xmlns="http://hl7.org/fhir">
    <id value="c804eca2-8b32-44d7-b654-b88bb9b1edd2" />
    <meta>
        <profile value="https://fhir.hl7.org.uk/StructureDefinition/UKCore-MedicationRequest" />
    </meta>
    <status value="active" />
    <intent value="order" />
    <category>
        <coding>
            <system value="http://terminology.hl7.org/CodeSystem/medicationrequest-category" />
            <code value="community" />
            <display value="community" />
        </coding>
    </category>
    <medicationCodeableConcept>
        <coding>
            <system value="https://dmd.nhs.uk" />
            <code value="321177003" />
            <display value="Zopiclone 3.75mg tablets" />
        </coding>
    </medicationCodeableConcept>
    <subject>
        <identifier>
            <system value="https://fhir.nhs.uk/Id/nhs-number" />
            <value value="9999999999" />
        </identifier>
    </subject>
    <authoredOn value="2020-05-15T15:00:00Z" />
    <requester>
        <reference value="urn:staff-1112" />
        <display value="Dr Maikeu Well" />
    </requester>
    <recorder>
        <reference value="urn:staff-1112" />
        <display value="Dr Maikeu Well" />
    </recorder>
    <dosageInstruction>
        <text value="1 tablet - during the night - oral - as required - up to a maximum of 7.5 milligram in 24 hours" />
        <timing>
            <repeat>
                <when value="NIGHT" />
            </repeat>
        </timing>
        <asNeededBoolean value="true" />
        <route>
            <coding>
                <system value="http://snomed.info/sct" />
                <code value="26643006" />
                <display value="oral" />
            </coding>
        </route>
        <doseAndRate>
            <doseQuantity>
                <value value="1" />
                <unit value="tablet" />
                <system value="http://snomed.info/sct" />
                <code value="428673006" />
            </doseQuantity>
        </doseAndRate>
        <maxDosePerPeriod>
            <numerator>
                <value value="7.5" />
                <unit value="milligram" />
                <system value="http://unitsofmeasure.org" />
                <code value="mg" />
            </numerator>
            <denominator>
                <value value="24" />
                <unit value="hour" />
                <system value="http://unitsofmeasure.org" />
                <code value="h" />
            </denominator>
        </maxDosePerPeriod>
    </dosageInstruction>
    <substitution>
        <allowedBoolean value="false" />
    </substitution>
</MedicationRequest>

{
    "resourceType": "MedicationRequest",
    "id": "c804eca2-8b32-44d7-b654-b88bb9b1edd2",
    "meta": {
        "profile":  [
            "https://fhir.hl7.org.uk/StructureDefinition/UKCore-MedicationRequest"
        ]
    },
    "status": "active",
    "intent": "order",
    "category":  [
        {
            "coding":  [
                {
                    "system": "http://terminology.hl7.org/CodeSystem/medicationrequest-category",
                    "code": "community",
                    "display": "community"
                }
            ]
        }
    ],
    "medicationCodeableConcept": {
        "coding":  [
            {
                "system": "https://dmd.nhs.uk",
                "code": "321177003",
                "display": "Zopiclone 3.75mg tablets"
            }
        ]
    },
    "subject": {
        "identifier": {
            "system": "https://fhir.nhs.uk/Id/nhs-number",
            "value": "9999999999"
        }
    },
    "authoredOn": "2020-05-15T15:00:00Z",
    "requester": {
        "reference": "urn:staff-1112",
        "display": "Dr Maikeu Well"
    },
    "recorder": {
        "reference": "urn:staff-1112",
        "display": "Dr Maikeu Well"
    },
    "dosageInstruction":  [
        {
            "text": "1 tablet - during the night - oral - as required - up to a maximum of 7.5 milligram in 24 hours",
            "timing": {
                "repeat": {
                    "when":  [
                        "NIGHT"
                    ]
                }
            },
            "asNeededBoolean": true,
            "route": {
                "coding":  [
                    {
                        "system": "http://snomed.info/sct",
                        "code": "26643006",
                        "display": "oral"
                    }
                ]
            },
            "doseAndRate":  [
                {
                    "doseQuantity": {
                        "value": 1,
                        "unit": "tablet",
                        "system": "http://snomed.info/sct",
                        "code": "428673006"
                    }
                }
            ],
            "maxDosePerPeriod": {
                "numerator": {
                    "value": 7.5,
                    "unit": "milligram",
                    "system": "http://unitsofmeasure.org",
                    "code": "mg"
                },
                "denominator": {
                    "value": 24,
                    "unit": "hour",
                    "system": "http://unitsofmeasure.org",
                    "code": "h"
                }
            }
        }
    ],
    "substitution": {
        "allowedBoolean": false
    }
}

MedicationRequest.id[0]	c804eca2-8b32-44d7-b654-b88bb9b1edd2
MedicationRequest.meta[0].profile[0]	https://fhir.hl7.org.uk/StructureDefinition/UKCore-MedicationRequest
MedicationRequest.status[0]	active
MedicationRequest.intent[0]	order
MedicationRequest.category[0].coding[0].system[0]	http://terminology.hl7.org/CodeSystem/medicationrequest-category
MedicationRequest.category[0].coding[0].code[0]	community
MedicationRequest.category[0].coding[0].display[0]	community
MedicationRequest.medication[0].coding[0].system[0]	https://dmd.nhs.uk
MedicationRequest.medication[0].coding[0].code[0]	321177003
MedicationRequest.medication[0].coding[0].display[0]	Zopiclone 3.75mg tablets
MedicationRequest.subject[0].identifier[0].system[0]	https://fhir.nhs.uk/Id/nhs-number
MedicationRequest.subject[0].identifier[0].value[0]	9999999999
MedicationRequest.authoredOn[0]	2020-05-15T15:00:00Z
MedicationRequest.requester[0].reference[0]	urn:staff-1112
MedicationRequest.requester[0].display[0]	Dr Maikeu Well
MedicationRequest.recorder[0].reference[0]	urn:staff-1112
MedicationRequest.recorder[0].display[0]	Dr Maikeu Well
MedicationRequest.dosageInstruction[0].text[0]	1 tablet - during the night - oral - as required - up to a maximum of 7.5 milligram in 24 hours
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].when[0]	NIGHT
MedicationRequest.dosageInstruction[0].asNeeded[0]	True
MedicationRequest.dosageInstruction[0].route[0].coding[0].system[0]	http://snomed.info/sct
MedicationRequest.dosageInstruction[0].route[0].coding[0].code[0]	26643006
MedicationRequest.dosageInstruction[0].route[0].coding[0].display[0]	oral
MedicationRequest.dosageInstruction[0].doseAndRate[0].dose[0].value[0]	1
MedicationRequest.dosageInstruction[0].doseAndRate[0].dose[0].unit[0]	tablet
MedicationRequest.dosageInstruction[0].doseAndRate[0].dose[0].system[0]	http://snomed.info/sct
MedicationRequest.dosageInstruction[0].doseAndRate[0].dose[0].code[0]	428673006
MedicationRequest.dosageInstruction[0].maxDosePerPeriod[0].numerator[0].value[0]	7.5
MedicationRequest.dosageInstruction[0].maxDosePerPeriod[0].numerator[0].unit[0]	milligram
MedicationRequest.dosageInstruction[0].maxDosePerPeriod[0].numerator[0].system[0]	http://unitsofmeasure.org
MedicationRequest.dosageInstruction[0].maxDosePerPeriod[0].numerator[0].code[0]	mg
MedicationRequest.dosageInstruction[0].maxDosePerPeriod[0].denominator[0].value[0]	24
MedicationRequest.dosageInstruction[0].maxDosePerPeriod[0].denominator[0].unit[0]	hour
MedicationRequest.dosageInstruction[0].maxDosePerPeriod[0].denominator[0].system[0]	http://unitsofmeasure.org
MedicationRequest.dosageInstruction[0].maxDosePerPeriod[0].denominator[0].code[0]	h
MedicationRequest.substitution[0].allowed[0]	False

MedicationRequest

id : c804eca2-8b32-44d7-b654-b88bb9b1edd2

meta

profile : https://fhir.hl7.org.uk/StructureDefinition/UKCore-MedicationRequest

status : active

intent : order

category

coding

system : http://terminology.hl7.org/CodeSystem/medicationrequest-category

code : community

display : community

medication

coding

system : https://dmd.nhs.uk

code : 321177003

display : Zopiclone 3.75mg tablets

subject

identifier

system : https://fhir.nhs.uk/Id/nhs-number

value : 9999999999

authoredOn : 2020-05-15T15:00:00Z

requester

reference : urn:staff-1112

display : Dr Maikeu Well

recorder

reference : urn:staff-1112

display : Dr Maikeu Well

dosageInstruction

text : 1 tablet - during the night - oral - as required - up to a maximum of 7.5 milligram in 24 hours

timing

repeat

when : NIGHT

asNeeded : True

route

coding

system : http://snomed.info/sct

code : 26643006

display : oral

doseAndRate

dose

value : 1

unit : tablet

system : http://snomed.info/sct

code : 428673006

maxDosePerPeriod

numerator

value : 7.5

unit : milligram

system : http://unitsofmeasure.org

code : mg

denominator

value : 24

unit : hour

system : http://unitsofmeasure.org

code : h

substitution

allowed : False

Zopiclone 3.75mg tablets, 1 tablet, at BEDTIME, PRN, oral

Example #2: Dosage.asNeededCodeableConcept

<!--    Metoclopramide, orally 10mg to be taken when required for nausea up to three times daily    -->
<MedicationRequest xmlns="http://hl7.org/fhir">
    <id value="e02e462c-12db-4162-95f6-0436a60c5bc4" />
    <meta>
        <profile value="https://fhir.hl7.org.uk/StructureDefinition/UKCore-MedicationRequest" />
    </meta>
    <status value="active" />
    <intent value="order" />
    <category>
        <coding>
            <system value="http://terminology.hl7.org/CodeSystem/medicationrequest-category" />
            <code value="inpatient" />
            <display value="inpatient" />
        </coding>
    </category>
    <medicationCodeableConcept>
        <coding>
            <system value="https://dmd.nhs.uk" />
            <code value="56549003" />
            <display value="Metoclopramide" />
        </coding>
    </medicationCodeableConcept>
    <subject>
        <identifier>
            <system value="https://fhir.nhs.uk/Id/nhs-number" />
            <value value="9999999999" />
        </identifier>
    </subject>
    <authoredOn value="2020-05-15T15:00:00Z" />
    <requester>
        <reference value="urn:staff-3040" />
        <display value="Dr Jim Bean" />
    </requester>
    <recorder>
        <reference value="urn:staff-3040" />
        <display value="Dr Jim Beam" />
    </recorder>
    <dosageInstruction>
        <text value="10 milligram - up to 3 times a day - oral - as required for nausea" />
        <timing>
            <repeat>
                <frequencyMax value="3" />
                <period value="1" />
                <periodUnit value="d" />
            </repeat>
        </timing>
        <asNeededCodeableConcept>
            <coding>
                <system value="http://snomed.info/sct" />
                <code value="422587007" />
                <display value="nausea" />
            </coding>
        </asNeededCodeableConcept>
        <route>
            <coding>
                <system value="http://snomed.info/sct" />
                <code value="26643006" />
                <display value="oral" />
            </coding>
        </route>
        <doseAndRate>
            <doseQuantity>
                <value value="10" />
                <unit value="milligram" />
                <system value="http://unitsofmeasure.org" />
                <code value="mg" />
            </doseQuantity>
        </doseAndRate>
    </dosageInstruction>
    <substitution>
        <allowedBoolean value="false" />
    </substitution>
</MedicationRequest>

{
    "resourceType": "MedicationRequest",
    "id": "e02e462c-12db-4162-95f6-0436a60c5bc4",
    "meta": {
        "profile":  [
            "https://fhir.hl7.org.uk/StructureDefinition/UKCore-MedicationRequest"
        ]
    },
    "status": "active",
    "intent": "order",
    "category":  [
        {
            "coding":  [
                {
                    "system": "http://terminology.hl7.org/CodeSystem/medicationrequest-category",
                    "code": "inpatient",
                    "display": "inpatient"
                }
            ]
        }
    ],
    "medicationCodeableConcept": {
        "coding":  [
            {
                "system": "https://dmd.nhs.uk",
                "code": "56549003",
                "display": "Metoclopramide"
            }
        ]
    },
    "subject": {
        "identifier": {
            "system": "https://fhir.nhs.uk/Id/nhs-number",
            "value": "9999999999"
        }
    },
    "authoredOn": "2020-05-15T15:00:00Z",
    "requester": {
        "reference": "urn:staff-3040",
        "display": "Dr Jim Bean"
    },
    "recorder": {
        "reference": "urn:staff-3040",
        "display": "Dr Jim Beam"
    },
    "dosageInstruction":  [
        {
            "text": "10 milligram - up to 3 times a day - oral - as required for nausea",
            "timing": {
                "repeat": {
                    "frequencyMax": 3,
                    "period": 1,
                    "periodUnit": "d"
                }
            },
            "asNeededCodeableConcept": {
                "coding":  [
                    {
                        "system": "http://snomed.info/sct",
                        "code": "422587007",
                        "display": "nausea"
                    }
                ]
            },
            "route": {
                "coding":  [
                    {
                        "system": "http://snomed.info/sct",
                        "code": "26643006",
                        "display": "oral"
                    }
                ]
            },
            "doseAndRate":  [
                {
                    "doseQuantity": {
                        "value": 10,
                        "unit": "milligram",
                        "system": "http://unitsofmeasure.org",
                        "code": "mg"
                    }
                }
            ]
        }
    ],
    "substitution": {
        "allowedBoolean": false
    }
}

MedicationRequest.id[0]	e02e462c-12db-4162-95f6-0436a60c5bc4
MedicationRequest.meta[0].profile[0]	https://fhir.hl7.org.uk/StructureDefinition/UKCore-MedicationRequest
MedicationRequest.status[0]	active
MedicationRequest.intent[0]	order
MedicationRequest.category[0].coding[0].system[0]	http://terminology.hl7.org/CodeSystem/medicationrequest-category
MedicationRequest.category[0].coding[0].code[0]	inpatient
MedicationRequest.category[0].coding[0].display[0]	inpatient
MedicationRequest.medication[0].coding[0].system[0]	https://dmd.nhs.uk
MedicationRequest.medication[0].coding[0].code[0]	56549003
MedicationRequest.medication[0].coding[0].display[0]	Metoclopramide
MedicationRequest.subject[0].identifier[0].system[0]	https://fhir.nhs.uk/Id/nhs-number
MedicationRequest.subject[0].identifier[0].value[0]	9999999999
MedicationRequest.authoredOn[0]	2020-05-15T15:00:00Z
MedicationRequest.requester[0].reference[0]	urn:staff-3040
MedicationRequest.requester[0].display[0]	Dr Jim Bean
MedicationRequest.recorder[0].reference[0]	urn:staff-3040
MedicationRequest.recorder[0].display[0]	Dr Jim Beam
MedicationRequest.dosageInstruction[0].text[0]	10 milligram - up to 3 times a day - oral - as required for nausea
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].frequencyMax[0]	3
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].period[0]	1
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].periodUnit[0]	d
MedicationRequest.dosageInstruction[0].asNeeded[0].coding[0].system[0]	http://snomed.info/sct
MedicationRequest.dosageInstruction[0].asNeeded[0].coding[0].code[0]	422587007
MedicationRequest.dosageInstruction[0].asNeeded[0].coding[0].display[0]	nausea
MedicationRequest.dosageInstruction[0].route[0].coding[0].system[0]	http://snomed.info/sct
MedicationRequest.dosageInstruction[0].route[0].coding[0].code[0]	26643006
MedicationRequest.dosageInstruction[0].route[0].coding[0].display[0]	oral
MedicationRequest.dosageInstruction[0].doseAndRate[0].dose[0].value[0]	10
MedicationRequest.dosageInstruction[0].doseAndRate[0].dose[0].unit[0]	milligram
MedicationRequest.dosageInstruction[0].doseAndRate[0].dose[0].system[0]	http://unitsofmeasure.org
MedicationRequest.dosageInstruction[0].doseAndRate[0].dose[0].code[0]	mg
MedicationRequest.substitution[0].allowed[0]	False

MedicationRequest

id : e02e462c-12db-4162-95f6-0436a60c5bc4

meta

profile : https://fhir.hl7.org.uk/StructureDefinition/UKCore-MedicationRequest

status : active

intent : order

category

coding

system : http://terminology.hl7.org/CodeSystem/medicationrequest-category

code : inpatient

display : inpatient

medication

coding

system : https://dmd.nhs.uk

code : 56549003

display : Metoclopramide

subject

identifier

system : https://fhir.nhs.uk/Id/nhs-number

value : 9999999999

authoredOn : 2020-05-15T15:00:00Z

requester

reference : urn:staff-3040

display : Dr Jim Bean

recorder

reference : urn:staff-3040

display : Dr Jim Beam

dosageInstruction

text : 10 milligram - up to 3 times a day - oral - as required for nausea

timing

repeat

frequencyMax : 3

period : 1

periodUnit : d

asNeeded

coding

system : http://snomed.info/sct

code : 422587007

display : nausea

route

coding

system : http://snomed.info/sct

code : 26643006

display : oral

doseAndRate

dose

value : 10

unit : milligram

system : http://unitsofmeasure.org

code : mg

substitution

allowed : False

Metoclopramide, orally 10mg to be taken when required for nausea up to three times daily

Element: `site`

Any site can be used from the SNOMED-CT hierarchy as a descendant of the concept 123037004 Body structure (body structure).

<!-- Site -->
<site>
    <coding>
        <system value="http://snomed.info/sct"/>
        <code value="59380008"/>
        <display value="Anterior abdominal wall structure"/>
    </coding>
</site>

Element: `route`

UKCore uses codes within the ePrescribing route of administration simple reference set (foundation metadata concept).

<!-- Route -->
<route>
    <coding>
        <system value="http://snomed.info/sct"/>
        <code value="78421000"/>
        <display value="Intramuscular route (qualifier value)"/>
    </coding>
</route>

Element: `method`

Note: Guidance on method under review to consider including use cases for when a free-text method instruction may be required.

The 999000041000001103 ePrescribing method simple reference set (foundation metadata concept) reference set collates the commonly used terms for method for use in the United Kingdom. Additional terms can be requested to be added to this reference set.

For example:

<!-- Method, using a preferred term -->
<method>
    <coding>
        <system value="http://snomed.info/sct"/>
        <code value="71791000001107"/>
        <display value="Nebulise - method of drug administration (qualifier value)"/>
    </coding>
</method>

and

<!-- Method, using a synonym -->
<method>
    <coding>
        <extension url="https://fhir.hl7.org.uk/StructureDefinition/Extension-UKCore-CodingSCTDescDisplay">
            <valueString value="Injection" />
        </extension>
        <system value="http://snomed.info/sct"/>
        <code value="129326001"/>
        <display value="Injection - action"/>
    </coding>
</method>

Whilst a FHIR value-set for method does exist, together with two separate hierarchies within SNOMED-CT (Dose form administration method and Dosing instruction fragment), it is recommended to use the ePrescribing reference set in the first instance.

Use of a free-text method

The method element with the Dosage structure can be populated with a free-text instruction. However, where a suitable coded SNOMED term exists, the coded term should always be used to allow the instruction to be machine-readable.

Scenarios exist where a suitable coded SNOMED term for method does not exist. For example, some paediatric-suitable methods of medication administration and where complex methods are required.

Example: Nystatin 100,000units/ml oral suspension sugar free for paediatric use.

<method>
   <text value="Rub onto the inside of the mouth and gums"/>
</method>

Example: Tiotropium bromide 18microgram inhalation powder capsules with device

<method>
   <text value="Inhale the contents"/>
</method>

Example: Creon capsules

<method>
   <text value="Swallowed whole or for ease of administration may be opened and the granules taken with acidic fluid or soft food but without chewing"/>
</method>

Considerations when mapping legacy dosage instructions to FHIR Dosage

Where an implementation approach is based on mapping of legacy text-based dosage instructions to the FHIR Dosage structure, the method described in text may not a like-for-like match a coded SNOMED method. In some cases there will be a suitable SNOMED coded term so we recommend involving clinicians during any mapping exercise.

For example. Some historic mouthwash medication records may use the text-based method within the dosage of "Rinse or Gargle". There is a coded SNOMED term of "Use as a mouthwash" (93481000001108) which could be more suitable.

Element: `doseAndRate`

The dose[x] and rate[x] elements within the Dosage structure have been combined in the FHIR R4 standard within doseAndRate. The underlying purpose and use is the same as per FHIR STU3 specification.

A dose or rate of medication can be described via one of the following methods. In both instances when considering Units of Measure note that UCUM is preferred.

Sub-element: `Dosage.doseAndRate.doseQuantity`

The amount of medication per dose, as a simple coded quantity.

<!-- Example A: 1 capsule -->
<doseAndRate>
    <doseQuantity>
        <value value="1"/>
        <unit value="capsule"/>
        <system value="http://snomed.info/sct"/>
        <code value="732937005"/>
    </doseQuantity>
</doseAndRate>

<!-- Example B: 30 milligrams -->
<doseAndRate>
    <doseQuantity>
        <value value="30"/>
        <unit value="milligram"/>
        <system value="http://unitsofmeasure.org"/>
        <code value="mg"/>
    </doseQuantity>
</doseAndRate>

Sub-element: `Dosage.doseAndRate.doseRange`

A dose that may be in a given low / high range.

<!-- for a dose between 7.5 to 30 milligram -->
<doseAndRate>
    <doseRange>
        <low>
            <value value="7.5"/>
            <unit value="milligram"/>
            <code value="mg"/>
            <system value="http://unitsofmeasure.org"/>
        </low>
        <high>
            <value value="30"/>
            <unit value="milligram"/>
            <code value="mg"/>
            <system value="http://unitsofmeasure.org"/>
        </high>
    </doseRange>
</doseAndRate>

A rate-based quantity, such as 30 ml per hour, can be expressed as a rateRatio with coded numerator and denominator values.

Where the unit of measure for the ratio is defined within UCUM (see Common UCUM Units), for example, “milliliter per hour”, it can also be expressed using the simpler rateQuantity structure.

If the doseRange.low is omitted it should be interpreted as as dose "up to" the upper limit.

<!-- for a dose up to 30 milligram -->
<doseAndRate>
    <doseRange>
        <high>
            <value value="30"/>
            <unit value="milligram"/>
            <code value="mg"/>
            <system value="http://unitsofmeasure.org"/>
        </high>
    </doseRange>
</doseAndRate>

Recommendation: The FHIR standard allows the doseRange.high to be omitted but it is recommended not to support this. The absence of an upper limit for a dose range would be clinical bad practice.

Sub-element: `Dosage.doseAndRate.rateRatio`

Where the rate is expressed as coded numerator and denominator values.

at a rate of 30ml/hour using rateRatio

<doseAndRate>
	<rateRatio>
		<numerator>
			<value value="30"/>
			<unit value="millilitre"/>
			<system value="http://unitsofmeasure.org"/>
			<code value="mL"/>
		</numerator>
		<denominator>
			<value value="1"/>
			<unit value="hour"/>
			<system value="http://unitsofmeasure.org"/>
			<code value="h"/>
		</denominator>
	</rateRatio>
</doseAndRate>

Sub-element: `Dosage.doseAndRate.rateQuantity`

Where the unit of measure applicable to a rate is defined within UCUM which is mathematically equivalent to defining the rate using the more complex rateRatio structure.

at a rate of 30ml/hour using rateQuantity

<rateQuantity>
	<value value="30"/>
	<unit value="milliliters per hour"/>
	<system value="http://unitsofmeasure.org"/>
	<code value="mL/h"/>
</rateQuantity>

at a rate of 1mcg/kg/hour using rateQuantity

<doseAndRate>
	<rateQuantity>
		<value value="1"/>
		<unit value="microgram per kilogram per hour"/>
		<system value="http://unitsofmeasure.org"/>
		<code value="ug/kg/h"/>
	</rateQuantity>
</doseAndRate>

Sub-element: `Dosage.doseAndRate.rateRange`

Where the unit of measure applicable to a rate range is defined within UCUM the rateRange structure can be used.

give at 1-2 litres per minute using rateRange

<doseAndRate>
    <rateRange>
		<low>
			<value value="1"/>
			<unit value="liter per minute"/>
			<system value="http://unitsofmeasure.org"/>
			<code value="L/min"/>
		</low>
		<high>
			<value value="2"/>
			<unit value="liter per minute"/>
			<system value="http://unitsofmeasure.org"/>
			<code value="L/min"/>
		</high>
	</rateRange>
</doseAndRate>

Period of no (zero) administration

Where a dosage instruction includes a defined period of no (zero) administration then the doseAndRate element can be specified with a 0 (zero) quantity.

<rateQuantity>
    <value value="0" />
    <unit value="millilitre per hour" />
    <system value="http://unitsofmeasure.org" />
    <code value="mL/h" />
</rateQuantity>

<rateQuantity>
    <value value="0" />
    <unit value="capsule"/>
    <system value="http://snomed.info/sct"/>
    <code value="732937005"/>
</rateQuantity>

Element: `maxDosePer`

Sub-element: `Dosage.maxDosePerPeriod`

Used to define a maxiumum dose over a given time period.

An example would be a Sumatriptan 6mg injection which can be repeated after an hour but not again over a 24 hour period. The maxDosePerPeriod is defined as 12mg/24hours.

The maxDosePerPeriod is defined for each dosage instruction. For a multi-sequence instruction it would therefore be possible to define different maximum dosing periods within different sequences of the complete instruction.

A real-world example of where this would be required has not yet been identified.

Maximum dose per period of 12mg/24 hour

<maxDosePerPeriod>
    <numerator>
        <value value="12"/>
        <unit value="milligram"/>
        <system value="http://unitsofmeasure.org"/>
        <code value="mg"/>
    </numerator>
    <denominator>
        <value value="24"/>
        <unit value="hour"/>
        <system value="http://unitsofmeasure.org"/>
        <code value="h"/>
    </denominator>
</maxDosePerPeriod>

Sub-element: `Dosage.maxDosePerAdministration`

Used to define a maximum dose for a single administration.

An example would be Anagrelide for which a single dose should not exceed 2.5 mg. The maxDosePerAdministration is defined as 2.5mg.

In many scenarios it is expected that the dosage.doseRange would be used instead of maxDosePerAdministration.

The maxDosePerAdministration is defined for each dosage instruction. For a multi-sequence instruction it would therefore be possible to define different maximum dose administrations within different sequences of the complete instruction.

A real-world example of where this would be required has not yet been identified.

Maximum dose per administration of 2.5mg

<maxDosePerAdministration>
    <value value="2.5"/>
    <unit value="milligram"/>
    <system value="http://unitsofmeasure.org"/>
    <code value="mg"/>
</maxDosePerAdministration>

Sub-element: `Dosage.maxDosePerLifetime`

Used to define the maximum cumulative dose over the lifetime of a patient.

An example would be Daunorubicin which may have a maximum cumulative dose of 600mg/m2 (based on the size of the patient). The maxDosePerLifetime is defined as 600 mg/m2.

The maxDosePerLifetime can be defined for each dosage instruction; which, for a multi-sequence instruction is illogical, as any maxDosePerLifetime is equally applicable to all dosage sequence that relate to the single medication coded concept.

Note: If a maxDosePerLifetime statement is required with a multi-sequence instruction, it is recommended to define it within the last / final sequence to ensure that the information is presented at the end of a the complete instruction, rather than th middle which could be overlooked.

Maximum dose over lifetime of the patient of 600 mg/m2

<maxDosePerLifetime>
    <value value="600"/>
    <unit value="milligram per square metre"/>
    <system value="http://unitsofmeasure.org"/>
    <code value="mg/m2"/>
</maxDosePerLifetime>

Implementation guide for interoperable medicines

Element: Dosage

Implementation guidance

Element: sequence

Sequential Instructions

Concurrent Instructions

Element: text

Implementation Example A

Implementation Example B

Element: additionalInstruction

additionalInstruction / when overlap

continue / stop instructions

as directed

Element: patientInstruction

Timing Elements: duration, bounds and count

Sub-elements: duration and durationMax

Sub-element: boundsDuration

Sub-elements: count and countMax

Timing Elements: when, offset, dayOfWeek, timeOfDay, event and code

Sub-elements: when and offset

Sub-elements: dayOfWeek and timeOfDay

Sub-element: event

Sub-element: code

Timing Elements: frequency and period

Examples of potentially confusing timing instructions

Element: asNeeded

Sub-element: Dosage.asNeeded[x]

Element: site

Element: route

Element: method

Use of a free-text method

Considerations when mapping legacy dosage instructions to FHIR Dosage

Element: doseAndRate

Sub-element: Dosage.doseAndRate.doseQuantity

Sub-element: Dosage.doseAndRate.doseRange

Sub-element: Dosage.doseAndRate.rateRatio

Sub-element: Dosage.doseAndRate.rateQuantity

Sub-element: Dosage.doseAndRate.rateRange

Period of no (zero) administration

Element: maxDosePer

Sub-element: Dosage.maxDosePerPeriod

Sub-element: Dosage.maxDosePerAdministration

Sub-element: Dosage.maxDosePerLifetime

Element: `sequence`

Element: `text`

Element: `additionalInstruction`

`additionalInstruction` / `when` overlap

Element: `patientInstruction`

Timing Elements: `duration`, `bounds` and `count`

Sub-elements: `duration` and `durationMax`

Sub-element: `boundsDuration`

Sub-elements: `count` and `countMax`

Timing Elements: `when`, `offset`, `dayOfWeek`, `timeOfDay`, `event` and `code`

Sub-elements: `when` and `offset`

Sub-elements: `dayOfWeek` and `timeOfDay`

Sub-element: `event`

Sub-element: `code`

Timing Elements: `frequency` and `period`

Element: `asNeeded`

Sub-element: `Dosage.asNeeded[x]`

Element: `site`

Element: `route`

Element: `method`

Element: `doseAndRate`

Sub-element: `Dosage.doseAndRate.doseQuantity`

Sub-element: `Dosage.doseAndRate.doseRange`

Sub-element: `Dosage.doseAndRate.rateRatio`

Sub-element: `Dosage.doseAndRate.rateQuantity`

Sub-element: `Dosage.doseAndRate.rateRange`

Element: `maxDosePer`

Sub-element: `Dosage.maxDosePerPeriod`

Sub-element: `Dosage.maxDosePerAdministration`

Sub-element: `Dosage.maxDosePerLifetime`