This code system http://hl7.org/fhir/medication-admin-category defines the following codes:

CodeDisplayDefinition
inpatientInpatientIncludes administrations in an inpatient or acute care setting
outpatientOutpatientIncludes administrations in an outpatient setting (for example, Emergency Department, Outpatient Clinic, Outpatient Surgery, Doctor's office)
communityCommunityIncludes administrations by the patient in their home (this would include long term care or nursing homes, hospices, etc)