A large proportion of cases, especially those where the medication are 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.
Units of Measure
A unit of measure is required when describing a dosage and can be supplied via one of the following:
UCUM
The Unified Code for Units of Measure (UCUM) is preferred and should be used where possible.
Examples of when a UCUM unit of measure would be used are:
- gram (g)
- milliliter (ml)
- percent (%)
SNOMED-CT
In the instance where a UCUM unit of measure is not defined, use a SNOMED-CT unit of measure instead.
Examples of where a SNOMED-CT unit of measure would typically be used are:
- tablet
- capsule
- ampoule
All units of measure are descendants of concept 767524001 | Unit of measure (qualifier value) | which includes both UCUM and non-UCUM codes.
Concept 732935002 | Unit of presentation (unit of presentation) |, which is also a descendant of the Unit of measure concept, holds a list non-UCUM units of measure that are used within prescribing, such as:
- tablet
- pad
- patch
Describing a dosage
A dosage can be described via one of the following methods. In both instances when considering Units of Measure note that UCUM is preferred.
Dosage.doseQuantity
The amount of medication per dose, as a simple coded quantity.
Dosage.doseRange
A dose that may be in a given low/high range.
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
- 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.