[Question] how do you actually verify concentration
The title is the whole question — how do you actually verify concentration — but here is why I am asking.
Started reconstituting everything to a round concentration and the six-in-the-morning error rate went to zero.
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.
Shook the first vial because nobody told me not to. It was fine, but I have swirled every one since.
Happy to answer the boring questions. Those are usually the ones worth asking.
best — the order this archive was captured in
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.
The lyophilised cake displaces a small volume, so the true concentration is very slightly lower than the arithmetic suggests. It is a fraction of a percent and it is dwarfed by fill tolerance.
This. Showing the working is the fastest way for somebody else to spot the mistake.
Disagree with the "more water is safer" framing. It is not safer, it is just a different number to divide by.
How many mg in the vial and how many mL are you adding?
Careful — that arithmetic is wrong. 30mg in 3mL is 10mg/mL, so 2mg draws to 20 units, not what you wrote.
twice as much water halves the concentration and doubles the units for the same dose
Reconstituted at 2mL when I meant to use a different volume. Caught it because the units looked wrong on the barrel. Now I write 10mg/mL on the glass before I put the cap back.
- 1This. Showing the working is the fastest way for somebody else to spot the…6 comments in this branch · started by u/rasmus_kuipers