[Discussion] the reconstitution advice in here is 3 years out of date
the reconstitution advice in here is 3 years out of date, and I am aware this is a minority view on this board. 3 years. Those are measured, not estimated, and not rounded up in my favour. Shook the first vial because nobody told me not to. It was fine, but I have swirled every one since. The dead space question sent…
The arithmetic in full: concentration is mass over volume, so 20mg into 2mL gives 10mg/mL. A U-100 syringe is graduated at 100 units per millilitre, so 5mg is 5 divided by 10 millilitres, which is 50 units.
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.
Correcting myself above: I wrote the concentration the wrong way up. Mass over volume, not volume over mass.
more water is not more drug, it is the same drug in a bigger volume
more water is not more drug, it is the same drug in a bigger volume
ahmed_rasmussen has the units point exactly right. They are a volume on the barrel and nothing else.
Careful — that arithmetic is wrong. 5mg in 2mL is 2.5mg/mL, so 1mg draws to 40 units, not what you wrote.
units are a volume on a U-100 syringe, not a dose
The arithmetic in full: concentration is mass over volume, so 20mg into 2mL gives 10mg/mL.
Right, and the arithmetic behind it: 15mg in 3mL is 5mg/mL, so 0.75mg is 15 units.