unpopular opinion: most of what gets said here about bacteriostatic water is guesswork
The title is the argument: unpopular opinion: most of what gets said here about bacteriostatic water is guesswork. Here is the rest of it.
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.
Not medical advice, obviously, and nothing here is approved for human use. One person with a spreadsheet.
best — the order this archive was captured in
The failure modes I have actually seen posted here, in order of frequency.
One: reconstituting at a different volume than intended and not writing it down, so the next draw is based on a remembered concentration. Two: treating units as a dose rather than a volume, which breaks the moment the concentration changes. Three: assuming a syringe is U-100 when it is not.
All three are solved by the same two habits — do the arithmetic before the water goes in, and write the result on the glass. Neither costs anything and between them they cover almost every question this board gets.
Asked GL Biochem what volume they reconstitute to for their own stability testing and they answered in one line. Useful thing to know.
Asked GL Biochem what volume they reconstitute to for their own stability testing and they answered in one line.
Right, and the arithmetic behind it: 5mg in 1mL is 5mg/mL, so 0.5mg is 10 units.
Agreed on the swirl. There is no reason to shake it and a good reason not to.
5mg into 1mL is 5mg/mL, and 1.5mg of that is 30 units
That only works if the fill weight is exactly the label weight, and it usually is not exactly anything.
Yes, and the dead-space point is worth repeating: it is small, it is real, and it is the same for every draw.
Agreed — units are volume. Once that lands, the rest of the arithmetic is one division.
This. Showing the working is the fastest way for somebody else to spot the mistake.
I keep a laminated card in the drawer with the arithmetic on it. Looks ridiculous. Has never once let me draw the wrong volume.
Correction: that gives 15 units, not what you have written. 10mg into 2mL is 5mg/mL and the division follows from there.
more water is not more drug, it is the same drug in a bigger volume
Cosigning the round-number approach. Reconstituting to something awkward is how you end up drawing 27.5 units at six in the morning.
Reconstituted at 3mL 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.
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