[Discussion] bacteriostatic water is doing more work than we give it credit for
The title is the argument: bacteriostatic water is doing more work than we give it credit for. 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.
Would rather be corrected in public than confident in private.
best — the order this archive was captured in
If your calculation produces a fraction of a unit, the concentration is wrong for your dose. Change the water volume until the numbers land on whole units.
Same. I got this wrong once, caught it because the units looked absurd, and have written on every vial since.
10mg into 1mL is 10mg/mL, and 1.5mg of that is 15 units
Wrote the date on the vial as well as the concentration after losing track of which one was opened first.
Wrote the date on the vial as well as the concentration after losing track of which one was opened first.
Disagreeing with this line only: adding more water is not a safety margin, it is a different divisor.
Asked SSA what volume they reconstitute to for their own stability testing and they answered in one line. Useful thing to know.
Careful — that arithmetic is wrong. 5mg in 1mL is 5mg/mL, so 2mg draws to 40 units, not what you wrote.
more water is not more drug, it is the same drug in a bigger volume
This. Showing the working is the fastest way for somebody else to spot the mistake.
units are a volume on a U-100 syringe, not a 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 2.5mg/mL on the glass before I put the cap back.
Correcting myself above: I wrote the concentration the wrong way up. Mass over volume, not volume over mass.
Disagree with the "more water is safer" framing. It is not safer, it is just a different number to divide by.
the number you write down is the number you will trust at 6am
Spent 15 weeks confused about this until somebody drew the table for me. 10mg, 1mL, 10mg/mL, 1mg is 10 units. That is the whole thing.
a U-100 syringe reads 100 units to the millilitre, every time
do the arithmetic before you reconstitute, not while holding a syringe
Corrected the concentration in the title, which contradicted the body. Nothing else touched.
I keep a laminated card in the drawer with the arithmetic on it. Looks ridiculous. Has never once let me draw the wrong volume.
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.