Adding constraints, bounds or limits to a dosage instruction

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

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, e.g. “for 7 days”
  • boundsRange - a low/high quantity, e.g. “for 2 to 3 weeks”
  • boundsPeriod - a date/time start to end period. e.g. “from 01/11/2018 to 10/11/2018”

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.

Tags: fhir