I’m seeking guidance on how to represent a combination therapy in MedicationDispense.dosageInstruction.
Our approach is to use one medication and represent the dosage as multiple dosageInstruction elements one for each dosage.
For example this medication is a combination of two drugs in one pill.
Brand Name: Xigduo XR
Drug Name: dapagliflozin/metformin hydrochloride extended release
Dosage: 10 mg/1,000 mg
A couple thoughts:
When there is a single precoordinated product code (e.g. MedicationDispense.medicationCodeableConcept) that conveys the strength of each ingredient (e.g. http://bioportal.bioontology.org/ontologies/RXNORM?p=classes&conceptid=1593058), then our implementation would have a single dosageInstruction where doseQuantity is something like 1 tablet or 2 capsules (unit of measure is based on drug form)
In other use cases when there isn’t a single over-arching product code available, such as a TPN order, then our implementation would have a single dosageInstruction where doseQuantity is the total bag volume and the MedicationDispense.medicationReference.product.ingredient.amount represents the quantity of each ingredient in the IV bag (e.g. 20 mg / 500 mL).
Note: you could convey the strength of each ingredient in the tablet, if you wanted, as follows:
MedicationDispense.medicationReference.product.ingredient.amount = 10mg/1 tab for dapagliflozin
MedicationDispense.medicationReference.product.ingredient.amount = 1000mg/1 tab for Metformin hydrochloride
We don’t do this when the code is precoordinated (we just use the MedicationDispense.medicationCodeableConcept), but you could use medicationReference as noted.
Thank you for your reply - this is helpful!
With further review of the standard we realized we were off track with using dosageInstruction to convey the ingredients.