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What do you do when anything is possible in terminologies?

 You’ve heard the saying that “anything is possible”. Whether you fully buy into this adage or not – this may actually make terminology work difficult. 

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For instance, you may have a use case that needs you to gather all Snomed CT and RxNorm codes for epinephrine + lidocaine injectable (drugs). So – what’s possible? Looking in the 3M HDD where we have different standards as well as varied client data, I can see all the different attributes; e.g., for ingredients, various standards/clients may choose to define drug concepts using the base ingredient or any of its salts, such as:

  • Epinephrine (base), Epinephrine bitartrate (salt), Epinephrine borate (salt), Epinephrine hydrochloride (salt): n=4
  • Lidocaine (base), lidocaine hydrochloride (salt), lidocaine hydrocarbonate (salt): n=3

So, for this two-ingredient drug, I need to consider 12 (4 X 3) different combinations of the bases/salts.

Now – what’s possible for “injectable” drugs?

Snomed CT uses a “Has manufactured dose form (attribute)” relationship to describe an intended route of administration in their dose form:

784976006 |Product containing precisely epinephrine 12.5 microgram/1 milliliter and lidocaine hydrochloride 20 milligram/1 milliliter conventional release solution for injection (clinical drug)

The HDD dose form domain gives me some more possibilities to add to the mix:

  • Powder for solution for injection
  • Powder for suspension for injection
  • Solution for injection (to find the Snomed CT concept above, I need this one)
  • Suspension for injection

So, 12 ingredient combos X 4 dose forms = 48 ways to look for matches, already.

RxNorm example 1:

1867994 |SCD| Epinephrine 0.005 MG/ML / Lidocaine Hydrochloride 15 MG/ML Injection

In the HDD route of administration domain, we find:

  • Injection (this is really a method of delivery and not a true route of administration – see its children):
    o  Intravenous
    o  Intramuscular
    o  Subcutaneous

Thus, 12 ingredient combos X 4 dose forms X 4 routes = 192 ways to look for matches.

RxNorm example 2:

1293648 |SCD| 1.7 ML Epinephrine 0.01 MG/ML / Lidocaine Hydrochloride 20 MG/ML Cartridge

We consider a cartridge to be a packaging, not a drug form nor a route of administration. However, it is often used to indicate injectable drugs.

Looking in the HDD Packaging domain for drugs that could be injected, we find:

  • Syringe
    o  Prefilled syringe
    o  Disposable syringe
    o  0.5 mL syringe, 1 mL syringe….
  • Autoinjector
  • Pen injector
  • Cartridge
  • Vial … and so on

So now my math will begin to blow up – too many packaging possibilities. For instance, in the RxNorm example 2, would I expect its packaging to be “Cartridge” or “1.7 mL Cartridge”? Both are correct – one more granular than the other. I’d better throw them both into “anything is possible” bucket. This is why broadening the search in terminologies by considering all possibilities may yield some interesting findings or a larger “catchment area” to support data aggregation, at the same time causing terminology mapping or identification challenges.

Please contact us if you have questions or if you’d like our help with terminologies and map sets!