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

Dosage.doseQuantity

The doseQuantity is one of two ways to describe a dose; the amount of medication per dose, as a simple coded quantity. The alternative is with a doseRange.

By preference, use UCUM units of measure (system URL: “http://unitsofmeasure.org”). Examples of when a UCUM unit of measure would be used are “gram” or “milliliter” or “percent”.

Where a UCUM unit of measure is not defined, use a SNOMED-CT unit of measure (system URL: “http://snomed.info/sct”).
Examples of when a SNOMED-CT unit of measure would typically be used are “tablet”, “capsule” or “ampule”.
Units of presentation relevant to medication dosage instructions are contained within the hierarchy as descendants of 732935002 | Unit of presentation.
Units of measure, where UCUM is not available, are contained within the hierarchy as descendants of 767524001 | Unit of measure.

Dosage.doseRange

The doseRange is used to describe a dose that may be in a given low/high range. By preference, use UCUM units of measure, but where not defined, use SNOMED-CT units.

Dosage.timing.repeat.frequency and Dosage.timing.repeat.period

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” and “every X period”.

The unit of the period must be one of the UCUM units; 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.