[Question] how do you actually verify mg/mL
how do you actually verify mg/mL. I would rather ask a basic question now than get this wrong quietly for two months.
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.
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.
I will update this if the picture changes rather than quietly leaving it up.
best — the order this archive was captured in
The arithmetic in full: concentration is mass over volume, so 10mg into 1mL gives 10mg/mL. A U-100 syringe is graduated at 100 units per millilitre, so 2mg is 2 divided by 10 millilitres, which is 20 units.
Left up and flaired Explainer — the numbers in this one check out.
Are you accounting for the powder volume, or is that where the confusion is?
label the vial with the date as well as the concentration
Wrote the date on the vial as well as the concentration after losing track of which one was opened first.
more water is not more drug, it is the same drug in a bigger volume
bacteriostatic water has the preservative, sterile water does not
Reconstituted at 1mL when I meant to use a different volume. Caught it because the units looked wrong on the barrel. Now I write 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.
What is written on the vial right now?
aim the stream at the glass wall, not at the cake
Bacteriostatic or plain sterile water?
Correction: that gives 30 units, not what you have written. 15mg into 3mL is 5mg/mL and the division follows from there.
- 1more water is not more drug, it is the same drug in a bigger volume8 comments in this branch · started by u/hedda_ekstrom