three years of mg/mL threads, summarised so you do not have to read them
three years of mg/mL threads, summarised so you do not have to read them — a position I have arrived at slowly and would like tested.
Why "more water" keeps confusing people, including me for a month.
The vial contains a fixed amount of peptide. Water changes nothing about that amount. What it changes is concentration, and concentration is the divisor between the dose you want and the volume you draw.
So doubling the water halves the concentration and doubles the units for the same dose. Nothing is diluted in any sense that matters; you are simply reading a bigger number off the same barrel. Pick the water volume that puts your usual dose on a whole number of units and life gets easier.
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.
The arithmetic in full: concentration is mass over volume, so 10mg into 3mL gives 3.33mg/mL. A U-100 syringe is graduated at 100 units per millilitre, so 0.5mg is 0.5 divided by 3.33 millilitres, which is 15 units.
Tell me where this is wrong. That is the useful part of posting it.
best — the order this archive was captured in
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 the maths gives you a fraction of a unit, change the concentration
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.
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.
Correction: that gives 100 units, not what you have written. 10mg into 2mL is 5mg/mL and the division follows from there.
Cosigning the round-number approach. Reconstituting to something awkward is how you end up drawing 27.5 units at six in the morning.
a U-100 syringe reads 100 units to the millilitre, every time
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.
Spent 14 weeks confused about this until somebody drew the table for me. 10mg, 2mL, 5mg/mL, 0.25mg is 5 units. That is the whole thing.
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.
Yes. Writing 5mg/mL on the vial takes four seconds and removes the entire class of error this board exists to fix.
Careful — that arithmetic is wrong. 10mg in 1mL is 10mg/mL, so 2mg draws to 20 units, not what you wrote.
What is written on the vial right now?
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.
write the concentration on the vial in marker, that is the whole post
Did the maths give you a whole number of units, or a fraction?
Wrote the date on the vial as well as the concentration after losing track of which one was opened first.
aim the stream at the glass wall, not at the cake
30mg into 3mL is 10mg/mL, and 2mg of that is 20 units
Asked SGN what volume they reconstitute to for their own stability testing and they answered in one line. Useful thing to know.
- 1Reconstituted at 2mL when I meant to use a different volume. Caught it…6 comments in this branch · started by u/bruno_dumitru