[Question] mg/mL — what am I missing here
Slightly embarrassed to be asking this, but: mg/mL — what am I missing here. 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. If your calculation produces a fraction of a unit, the concentration…
Agreed on the swirl. There is no reason to shake it and a good reason not to.
Disagree with the "more water is safer" framing. It is not safer, it is just a different number to divide by.
Pushback on the syringe advice: a U-100 barrel reads units of volume. Calling them "doses" is how the confusion starts.
Cosigning the round-number approach. Reconstituting to something awkward is how you end up drawing 27.5 units at six in the morning.
aim the stream at the glass wall, not at the cake
Are you accounting for the powder volume, or is that where the confusion is?
write the concentration on the vial in marker, that is the whole post
Wrote the date on the vial as well as the concentration after losing track of which one was opened first.
Reconstituted at 1mL when I meant to use a different volume. Caught it because the units looked wrong on the barrel. Now I write 5mg/mL on the glass before I put the cap back.
Careful — that arithmetic is wrong. 15mg in 3mL is 5mg/mL, so 2.5mg draws to 50 units, not what you wrote.
What concentration did you actually reconstitute at, rather than what did you intend to?