u/julia_erdogan

Is the compound still on the shortage list where you are?

Yes. Writing 2.5mg/mL on the vial takes four seconds and removes the entire class of error this board exists to fix.

5mg into 3mL is 1.67mg/mL, and 0.5mg of that is 30 units

Spent 6 weeks confused about this until somebody drew the table for me. 10mg, 2mL, 5mg/mL, 2.5mg is 50 units. That is the whole thing.

Bacteriostatic water contains benzyl alcohol as a preservative, which is what makes repeated entry into the same vial reasonable. Plain sterile water has no preservative.

Is there a deadline on the notice?

swirl, never shake

Agreed — units are volume. Once that lands, the rest of the arithmetic is one division.

Compounded preparations are not approved products and carry no bioequivalence claim. That is a statement about regulatory category, not about quality.

Pushback on the syringe advice: a U-100 barrel reads units of volume. Calling them "doses" is how the confusion starts.

clearance time is not carrier time

the number you write down is the number you will trust at 6am

I would not read the price difference as a quality signal.

Agreed — and the follow-up question is what the beyond-use date is based on.

Shipped from regional stock or from origin?

A beyond-use date derived from published stability data means something different from one assigned by default rule. Asking which is a fair question and the answer is usually available.

if the maths gives you a fraction of a unit, change the concentration

Cosigning the beyond-use date question. What it is based on tells you whether anybody has done stability work.

potency testing on the finished preparation is the thing to ask for

Who is the prescriber, and are they the same organisation as the pharmacy?

Careful. Naming a clinic without describing what actually happened turns this into a different kind of thread.

Asked the supplier what documentation travels with the shipment and got a straight answer. That was reassuring in itself.

the label on a compounded vial is a legal document, read it

Small fix — 503B facilities register with the regulator; 503A pharmacies are licensed by the state board. Different mechanisms.

Right, and the concentration genuinely can differ from the branded product, which breaks people’s arithmetic.

Correction: that gives 50 units, not what you have written. 10mg into 1mL is 10mg/mL and the division follows from there.

Same. I got this wrong once, caught it because the units looked absurd, and have written on every vial since.