Open the medication fridge at almost any weight-loss clinic and you’ll find them: half-used vials of compounded semaglutide, each with a beaten-up sticker showing the date it was first punctured. Some have a few tenths of a milligram left. Some are nearly full. All of them are on a clock, and most will go in the sharps bin with medicine still inside.
I run Zvia, a cash-pay med spa in Lakewood, Colorado, and I also build the software it runs on — so I’ve stood at that fridge doing the arithmetic in my head. The vial isn’t the leak. The leak is the gap between how a GLP-1 dose is prescribed, how it’s drawn, and how a generic inventory system counts — three different units that never quite line up, and money falling through every seam.
The ladder is in milligrams. The syringe is in units. The vial is neither.
A standard semaglutide titration climbs in milligrams: 0.25 mg a week to start, then 0.5, 1.0, 1.7, and 2.4 mg, usually stepping up about every four weeks as the patient tolerates it. Your prescriber sets the actual schedule — this is the shape of it, not clinical advice.
But nobody draws “milligrams.” They draw units on a U-100 insulin syringe, where 100 units is 1 mL. And the vial is labeled in a concentration — say 2.5 mg per mL. Those three facts have to be reconciled at every single visit:
- 0.25 mg ÷ 2.5 mg/mL = 0.1 mL = 10 units
- 0.5 mg = 0.2 mL = 20 units
- 1.0 mg = 0.4 mL = 40 units
- 1.7 mg = 0.68 mL = 68 units
- 2.4 mg = 0.96 mL = 96 units
Change the concentration and every number moves. At 5 mg/mL, 10 units is no longer 0.25 mg — it’s 0.5 mg, twice the dose. “Ten units” means nothing without the concentration written next to it. This is the first place a clinic gets hurt: a record that stores the dose as “10 units” has thrown away the one fact that makes 10 units meaningful.
A multi-dose vial is a draw-down with a deadline
A single vial holds many doses. Say it’s a 10 mg vial at 2.5 mg/mL — 4 mL, enough for forty 0.25 mg draws on paper. You never get forty. The moment it’s punctured, the compounding pharmacy’s beyond-use date starts running — often around 28 days for a multi-dose vial, though it varies by preparation. (Beyond-use dating follows USP standards and the pharmacy’s own testing; it’s on the label, not something you set — and none of this is legal or clinical advice.)
So the vial is a draw-down racing a deadline. A patient in their first month pulls 0.25 mg once a week — four draws, 1 mg — and on day 28 the vial hits its beyond-use date with 9 mg still in it. Nine milligrams you paid for, discarded.
Run the honest number. If the whole vial had been drawn before its date, it cost you vial price ÷ 10 mg per delivered milligram. Discarded at 1 mg delivered, it cost ten times that per milligram that actually reached a patient. Same vial, same price — ten times the real cost, and the difference is pure discard nobody ever charged for.
Generic inventory counts vials. The cost lives in the milligrams.
Here’s why the med-spa POS or generic inventory tool can’t show you any of this: it counts whole units. A vial is one item. It goes “in stock,” then “used,” and the system’s model of the world has no place to put 0.25 mg out of 10. So one of two things happens. Either the vial decrements as a whole the first time it’s touched — and now every dose after that is invisible, drawn from a vial the system already believes is gone. Or it never decrements until someone remembers to mark it empty — and the 9 mg you discarded at the beyond-use date simply vanishes, uncharged and unrecorded.
Either way the fractional dose and its true cost disappear. You can’t see cost per delivered milligram, because nothing ever tracked milligrams. You can’t see which vials died with medicine in them, because “partial” isn’t a state the system can hold. The waste is real and the ledger is blind to it.
The workflow that keeps the milligrams honest
You can run this by hand — I did for a long time — and the discipline is the same whether it’s on paper or in software:
- Log the vial in milligrams, not units. When it’s received and again when it’s punctured, record the lot number, the concentration, the total milligrams, and the beyond-use date from the label. That date is the clock everything else runs against.
- Record every draw in both mg and units, at that vial’s concentration. The chart gets the dose in milligrams; the person holding the syringe gets the units for this vial. Deduct the milligrams drawn from that specific vial’s remaining balance.
- Tie the draw to the chart and the charge in the same motion. A partial dose that isn’t on the patient’s record and isn’t on a charge is a dose you gave away and can’t account for later.
- Watch remaining mg against the beyond-use date. When a vial is going to reach its date with milligrams left, that’s a discard about to happen — surface it before it does, so the provider can decide what the remainder is for. That decision is clinical and it’s theirs; the ledger’s only job is to make the discard visible in time to have the conversation.
What the number is actually for
I built ProtokolIQ so the clinic doesn’t have to run that ledger in someone’s head: it records each vial as a quantity of milligrams at its stated concentration, ties every partial draw to the patient’s chart and the charge, and surfaces the beyond-use date while there are still milligrams left to account for.
That’s the whole claim, and it’s a small one. It doesn’t save you money — it shows you the money: the cost per delivered milligram, and the vial about to expire half-full, in time to do something about it. What you do is yours — stock a different vial size, build the program’s pricing around the real cost, or decide the convenience is worth the discard. The point is only that the number stops being a surprise you meet at the fridge, one expired vial at a time.