reading bacteriostatic water threads from 2024 and half of it aged badly
reading bacteriostatic water threads from 2024 and half of it aged badly. Change my mind, genuinely — I have no stake in being right about this. The dead space question sent me down a rabbit hole for a week. It is a fraction of a unit and it is the same every draw. Spent 13 weeks confused about this until somebody…
bacteriostatic water has the preservative, sterile water does not
Started reconstituting everything to a round concentration and the six-in-the-morning error rate went to zero.
aim the stream at the glass wall, not at the cake
What is written on the vial right now?
Not quite. Bacteriostatic and sterile water are not interchangeable for a multi-draw vial, and the difference is the preservative.
Disagree with the "more water is safer" framing. It is not safer, it is just a different number to divide by.
I would not round that figure. At 2.5mg/mL a rounding error of two units is a real fraction of the intended amount.
The arithmetic in full: concentration is mass over volume, so 20mg into 3mL gives 6.67mg/mL. A U-100 syringe is graduated at 100 units per millilitre, so 1mg is 1 divided by 6.67 millilitres, which is 15 units.
Is that a U-100 syringe? The barrel markings change the answer completely.
That is sterile water, not bacteriostatic. Same appearance, different product, and it matters for a multi-draw vial.
Cosigning the round-number approach. Reconstituting to something awkward is how you end up drawing 27.5 units at six in the morning.