How to store drug concentrations?

Hi all,

Let’s start off two examples:

  1. KETAMINE, 50mg/ml, 5ml, Amp.
  2. SODIUM CHLORIDE, 0.9%, 500ml, Drops

How would you store this, assuming you wouldn’t go into using drug ingredients, that’d add too much complexity in our setup. In that case I’m wondering as to where those concentrations should go.

Option 1:

Concept Dosage form Strength
KETAMINE Amp. 5ml - 50mg/ml
SODIUM CHLORIDE Drops 500ml - 0.9%

That’d be, keeping granularity on the concepts that represent the active components (KETAMINE, SODIUM CHLORIDE), but somehow hacking onto the strength (in a way that it’d remain parsable).

Option 2:

Concept Dosage form Strength
KETAMINE - 50mg/ml Amp. 5ml
SODIUM CHLORIDE - 0.9% Drops 500ml

That’d be taking the stance that a specific concentration is the active component (KETAMINE - 50mg/ml, SODIUM CHLORIDE - 0.9%).

We need an appropriate way to store this in an IPD setup without firing a bullet in our own foot in terms of potential for future reporting. I’ve got a feeling that option 1 is probably acceptable, but it’d be great to get the lights of clinicians and health informatics specialists out there.

Cc @burke, @jteich, @janflowers, @akanter, @jdick, @rdahlman3, @ball, @jesplana

You might look at this file which is used to create drug metadata with the underlying concept. Note that we use concept reference mapping – some are CIEL, but most are likely PIH mappings.

I think it is important to separate out forms that are used for managing stock and forms used for managing administration to patients. In the examples above 50mg/ml is the strength. 5 ml is the packaging volume. A patient would receive something like 200mg IV which would be 4ml of the 50mg/ml solution. For the sodium chloride solution… it is actually .9% concentration and the 500ml is the volume in the bottle (unlikely to be drops in this example).

Consider that a prescription is likely to include either the total dose (500 mg by mouth once per day) or administration quantities (250mg tabs 2 tabs by mouth once per day). You will never see the packaging amount in the administration, only in managing the stock. Does that make sense? @jteich, do you agree?

Yes, I do.

Concept Form Strength Supplied unit - (for pharmacy stocking use)
KETAMINE IV solution 50mg/ml 5 ml ampoule
SODIUM CHLORIDE IV solution 0.9% 500 ml bag

Then an order might be:

Concept Strength Form Dose Route Frequency Duration Start
Ketamine 50mg/ml solution 200mg IV x1 now
Sodium chloride 0.9% solution 1000ml IV x1 now

The pharmacy and the nurse will figure out what packages to use.

(PS Note that orderers commonly leave out the Form for IV orders)

Thanks @ball, @akanter and @jteich

That’s very possible! :wink: I gathered that one from combining two drugs lists.

@jteich thank you for outlining the differences between how the drug are stored vs how corresponding drug orders may look like.

The latter leads me to a fundamental question for us, would it be ok to use a drug order to describe how drugs are used in an IPD setup? Very much like your second table is suggesting.

Not quite sure I fully understand “how drugs are used” in the question, but – my second representation would be used by physicians who are writing orders in IPD, and by nurses who are administering the drugs. The nurses would also need a medication administration record (MAR) functionality, which allows them to document when the drugs are actually given. And the pharmacy would be more concerned with stocking and dispensing, so they would use something like the first table. But yes, the medication order pretty much describes the patient’s active drug regimen.

There are a few other fields of importance, such as PRN (sometimes called SOS) which indicates that the drug is only supposed to be given if there is a reason – such as Paracetamol 650 mg every 4 hours PRN headache. So, there’s a little more to make a complete data model, and it has been discussed in past Design meetings, or I can help.