Implementation guide for interoperable medicines

This guidance is under active development by NHS England and content may be added or updated on a regular basis.

Common Principles

The following applies to the presentation of any component part of the dosage instruction;

  1. In most cases, express numbers as numbers, e.g. 3 not three. There are suggested exceptions:
  • 1.1. Refer to the section below when dealing with frequency data for the case of once or twice.
  • 1.2. When a proceeding unit of measure starts with a number, e.g. 5ml spoonful separate the quantity from the unit of measure with a x symbol, e.g. 2 x 5ml spoolful. Alternatively when the quantity is 1 or 2 is may be preferrable to express the quantity in words, e.g. ONE or TWO, e.g. TWO 5ml spoonful. Both options prevent misreading as a 25ml spoonful.
  • 1.3. Where a decimal number, e.g. 0.5 AND the unit of measure is NOT an SI unit AND the quantity is N.25, N.5 or N.75, then express using the words quarter, half or three quarters, e.g. half tablet, otherwise express as a decimal number, e.g. 12.5 milligram.

  1. Always express units of measure using the full description, e.g. milligram not mg. An exception is when the unit of measure as part of a pre-coordinated dm+d concept descriptions, e.g. Ramipril 5mg capsules.

  2. Always express a time-based unit of measure in the plural when applicable, e.g. 2 hour becomes 2 hours.

  3. Do not express other units of measure in the plural as this introduces complications with units such as microgram per millilitre or microgram per kilogram per hour.

  4. Separate multiple when statements with a comma plus whitespace. FHIR intreprets multiple when events as the union of these events so no extra textual expression is required. For example, if when=NORM and when=C then express as during the morning, at a meal.

  5. Separate multiple events statements with a comma plus whitespace. As these are separate events, for a more readable dosage instruction, consider replacing the last comma separating the final two statements with the word " and ", e.g. on 25/01/2019, 25/02/2019 and 25/03/2019.

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