[Question] how do you actually verify units
Asking properly rather than in a comment on somebody else’s thread: how do you actually verify units.
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.
Research-use-only material is not approved for human use and nothing here should be read as a recommendation to use 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.
Not quite. Bacteriostatic and sterile water are not interchangeable for a multi-draw vial, and the difference is the preservative.
10mg into 1mL is 10mg/mL, and 1.5mg of that is 15 units
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.
Are you accounting for the powder volume, or is that where the confusion is?
I would not round that figure. At 30mg/mL a rounding error of two units is a real fraction of the intended amount.
That only works if the fill weight is exactly the label weight, and it usually is not exactly anything.
What is written on the vial right now?
units are a volume on a U-100 syringe, not a dose
Agreed — units are volume. Once that lands, the rest of the arithmetic is one division.
reconstituting at a round concentration makes every later dose easy
Right — the volume you add is the only variable you control here, and the cake does not change it meaningfully.
Correction: that gives 30 units, not what you have written. 15mg into 3mL is 5mg/mL and the division follows from there.
if the maths gives you a fraction of a unit, change the concentration
Working has to be shown on arithmetic posts. Added a note asking for it rather than removing this one.
What concentration did you actually reconstitute at, rather than what did you intend to?
Agreed on the swirl. There is no reason to shake it and a good reason not to.
Yes, and the dead-space point is worth repeating: it is small, it is real, and it is the same for every draw.
This. Showing the working is the fastest way for somebody else to spot the mistake.
- 1reconstituting at a round concentration makes every later dose easy9 comments in this branch · started by u/lyophile_lou