FHIR Chat · Medication ingredient quantity · implementers

Stream: implementers

Topic: Medication ingredient quantity

David Moorhouse (Feb 20 2019 at 02:17):

We are implementing MedicationDispense for compounded medications and have a contained Medication resource to describe the item being dispensed. Our business requirements specify a quantity attribute on each ingredient of the compound.
I can't see an obvious way to code this within the FHIR R4 resources.
Here's a 2 ingredient example with Quantity, Brand, Strength, Form attributes:
Qty =7ml, Brand=BIODONE, Strength=2mg/ml, Form=Liquid
Qty=273ml ,Brand=WATER Tap

I can map the Brand/Strength/Form via the itemCodeableConcept attribute

How do I map the Quantity (which has value and unit attributes )?

Does this call for an extension ?

Lloyd McKenzie (Feb 20 2019 at 04:09):

You use Medication to define the compound - it can be a contained resource if it's not a standard compound

David Moorhouse (Feb 20 2019 at 04:19):

Thanks Lloyd. Medication has a quantity attribute which applies to the whole medication. Is there a similar concept for the ingredients e.g.

<Medication>
  <ingredient>
    <!-- ?? where to put the quantity in this ingredient node ?? ->
                <itemCodeableConcept>
                    <coding>
                        <system value="some coding system"/>
                        <code value="387253001"/>
                        <display value="BIODINE"/>
                    </coding>
                </itemCodeableConcept>
                <strength>
                    <numerator>
                        <value value="2"/>
                        <system value="http://unitsofmeasure.org"/>
                        <code value="mg"/>
                    </numerator>
                    <denominator>
                        <value value="1"/>
                        <system value="http://unitsofmeasure.org"/>
                        <code value="ml"/>
                    </denominator>
                </strength>
            </ingredient>
  </ingredient>
<!-- ingredient for water -->
</Medication>

Lloyd McKenzie (Feb 20 2019 at 04:57):

Medication has an ingredient property and each ingredient can have it's own strength (which is the amount of the ingredient in the overall med)

David Moorhouse (Feb 20 2019 at 20:55):

I'm not sure this covers our use case. In this example the ingredient has its own strength (e.g. 2mg/ml) - which we can code into the strength attribute - but then the ingredient has a specific quantity within the final mixture (7ml out of the 280 total).
Are you suggesting that we calculate the final strength e.g 2mg/ml *7ml/280ml gives a final strength of 0.05mg/ml so code this up as

<Medication>
    <ingredient>
        <itemCodeableConcept>
            <coding>
                <system value="http://snomed.info/sct"/>
                <code value="51758009"/>
                <display value="Methodone"/>
            </coding>
            <text value="7ml Biodine 2mg/ml"/>
        </itemCodeableConcept>
        <strength>
            <numerator>
                <value value="50"/>
                <system value="http://unitsofmeasure.org"/>
                <code value="mcg"/>
            </numerator>
            <denominator>
                <value value="1"/>
                <system value="http://unitsofmeasure.org"/>
                <code value="ml"/>
            </denominator>
        </strength>
    </ingredient>
    <ingredient>
        <itemCodeableConcept>
            <coding>
                <system value="http://snomed.info/sct"/>
                <code value="346712003"/>
                <display value="Water"/>
            </coding>
            <text value="273ml Tap Water"/>
        </itemCodeableConcept>
    </ingredient>
</Medication>

Jean Duteau (Feb 20 2019 at 21:02):

The strength data element on medication.ingredient is the strength relative to the entire medication. Depending on what you are specifying as the ingredient, it would either be 0.05mg/ml (for Methadone) or 7ml/280ml (for Biodone). With your initial request: Qty =7ml, Brand=BIODONE, Strength=2mg/ml, Form=Liquid
Qty=273ml ,Brand=WATER Tap

I would have gone with 7ml/280ml as it is the strength of this ingredient Biodone that you are specifying.

Melva Peters (Feb 20 2019 at 21:19):

There are a number of examples in the MedicationDispense resource that may help with your question.

David Moorhouse (Feb 20 2019 at 21:54):

Thx Jean and Melva, I've gone through the examples in more detail, the most useful is Medication 319 (https://www.hl7.org/fhir/medicationexample0319.xml.html) which describes a 3 ingredient ointment, where all ingredient strengths are specified against a base of 100g

I will run with the base of 280ml and show the ingredients as constituents of that

Last updated: Apr 12 2022 at 19:14 UTC