# How to model a cohesive medication order including several drugs

**Category:** [Ask IEB](https://discourse.openehr.org/c/ask-ieb/37)
**Created:** 2024-07-01 09:26 UTC
**Views:** 121
**Replies:** 2
**URL:** https://discourse.openehr.org/t/how-to-model-a-cohesive-medication-order-including-several-drugs/5417

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## Post #1 by @Lucas

Finally, our modeling efforts at our company Cistec in Switzerland are taking root in the application, and I am happy, that soon we can take the first medication orders in our EHR on top of openEHR. Along the requirements analysis and specification, I came along one important issue, that we were able to discuss with Heather Leslie on March 6, 2024. 

CONTEXT:
Due to the importance of this requirement, I decided to include a breaking change compared to the archetype INSTRUCTION.medication_order.v3 in the international CKM. This resulted in a change request by Heather Leslie - thank you Heather - on April 03, 2024, which is still pending.  And the breaking change is rather simple, namely increasing the cardinality (or occurences) of the slot "Medication details" in the archetype INSTRUCTION.medication_order.v3 from 0..1 to 0..*.

REQUIREMENT:
Ths inclusion of this breaking change is based on the following scenario:

Due to persistent nausea and vomiting, the resident decides to update the medication order for "Diclofenac" - a NSAID - from oral to intravenous use. This results, in a medication order with 1 Ampoule of Diclofenac 75mg (in 3mL), a carrier solution (100 mL NaCl - sodium chloride)  and a buffer (Sodium bicarbonate 8.4% in 10mL) sharing the same therapeutic directions.  

REASON FOR BREAKING CHANGE:
Instead of creating three different instances based on the archetype INSTRUCTION.medication_order.v3, I decided to update the cardinality of the slot "Medication details", such that I can instantiate one medication order with these three drugs/items sharing the same therapeutic direction and thus the clinical instructions.

MY QUESTION TO THE COMMUNITY:
As the change request is still pending, I wanted to ask in the community how you actually resolve the previous scenario in openEHR?

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## Post #2 by @ian.mcnicoll

The original design did understand this requirement but the decision (based on feedback from EPMA provides like DIPS and Better, amongst others) was that there should be a single 'top-level' Medication cluster to represent the combined product 'in the bag'

So  I would have done

```
 Medication Order: 
        Name:  "Diclofenac  infusion"
     Medication cluster:
           Name:"Diclofenac + Saline + Bicarb"
           Form:  "Infusion"
          Category: "Ad-hoc mixture"
         Amount: 113mls
                Medication cluster:
                         Name:"Diclofenac 75mg in 3ml"
                         Form:  "Infusion"
                        Category: "Active ingredient"
                        Amount: 3 ml
                  Medication cluster:
                         Name:"Sodium bicarbonate 8.4% in 10mL"
                         Form:  "Infusion"
                        Category: "Excipient"
                        Amount: 10 ml
                Medication cluster:
                         Name:"Normal saline"
                         Form:  "Infusion"
                        Category: "Excipient"
                        Amount: 100 ml
```

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## Post #3 by @Lucas

Yesterday, during the requirements' analysis for the medication administration I came across a solution, which is actually quite neat and also applies for a medication order. The solution stems from the medication administration applied in Better Meds.

Solution:
The archetype CLUSTER.medication.v2 (Medication details) includes an attribute called "Constituent" as a CLUSTER slot and occurrences set to 0..* by default. The solution consists of setting a CLUSTER.medication.v1 as wrapper and list all ingredients/medications separately in this cluster in the attribute "Constituent", also using the same CLUSTER.medication.v2. This results, that I can revert the breaking change, which is unnecessary.

Using a picture, this would look as follows (don't mind the eradicated attributes in the picture, they just show, which have been constraint to 0..0)
![image|619x500](upload://p51hNtkjWF703H9O5TRwpFs1Ygo.jpeg)

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**Canonical:** https://discourse.openehr.org/t/how-to-model-a-cohesive-medication-order-including-several-drugs/5417
**Original content:** https://discourse.openehr.org/t/how-to-model-a-cohesive-medication-order-including-several-drugs/5417