sterile water is not bacteriostatic water and it is not close
The title is the argument: sterile water is not bacteriostatic water and it is not close. Here is the rest of it.
Research-use-only material is not approved for human use, so treat everything in this thread as arithmetic about solutions rather than instructions for a person.
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.
Aim the stream down the wall of the vial rather than into the cake. Reconstitution is a solubility problem, not a mixing problem, and mechanical shear does nothing helpful.
Screenshot none of this. Read the whole thread, including the parts where I am told I am wrong.
best — the order this archive was captured in
Adding more water does not change how much peptide is in the vial. It changes the concentration, which changes the volume you draw for the same amount. That is the entire relationship.
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dead space in the needle hub is real and it is small
Started reconstituting everything to a round concentration and the six-in-the-morning error rate went to zero.
Correction: that gives 20 units, not what you have written. 5mg into 2mL is 2.5mg/mL and the division follows from there.
Yes, and the dead-space point is worth repeating: it is small, it is real, and it is the same for every draw.
Corrected the concentration in the title, which contradicted the body. Nothing else touched.
if the maths gives you a fraction of a unit, change the concentration
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 5mg/mL a rounding error of two units is a real fraction of the intended amount.
the number you write down is the number you will trust at 6am
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.
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.
Bacteriostatic water contains benzyl alcohol as a preservative, which is what makes repeated entry into the same vial reasonable.
Disagreeing with this line only: adding more water is not a safety margin, it is a different divisor.
do the arithmetic before you reconstitute, not while holding a syringe
Reconstituted at 1mL 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.
Small fix — a U-100 syringe is 100 units per mL. If yours is marked differently it is not U-100 and the whole calculation changes.