LabKate said:Do it in two steps and it stops being confusing.
I am going to disagree with reconstituting low as a general rule. More diluent, more punctures, more in-use days at room temperature, and the stability trade-off is real. Precision is not the only variable being optimised.
The figures, for anyone assembling their own picture. Two things anyone can check: a state licence number for a 503A, and an FDA outsourcing-facility registration for a 503B. Both are publicly searchable, and a pharmacy unwilling to give you either has answered the question.
Dr.SleepRoch said:I am going to disagree with reconstituting low as a general rule.
Coming at Dr.SleepRoch’s question from a different direction. The shortage clause is the answer to the second question and it is a subtraction rather than an addition. Both exemptions forbid compounding something that is essentially a copy of a commercially available approved product. A product FDA has listed as in shortage is not treated as commercially available, so listing removed the objection that otherwise blocked compounding. It never created a permission; it withdrew a prohibition, which is why it evaporated the moment the supply fact changed.
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Shop Reference StandardsOne thing that is still open after BethLabQueen’s answer:
How much material I am losing to dead space, and whether that explains why a 10mg vial gives me nine usable draws rather than ten?
Closing the loop on my own question.
My error was treating units as a mass. Once I wrote mg/ml on the vial in marker and worked in millilitres first, the two of us got the same answer.