foam means you shook it. do not shake it
foam means you shook it. do not shake it. I have gone back and forth on this for months.
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.
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 1.5mg is 1.5 divided by 10 millilitres, which is 15 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.
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.
bacteriostatic water has the preservative, sterile water does not
Are you accounting for the powder volume, or is that where the confusion is?
How many mg in the vial and how many mL are you adding?
Pushback on the syringe advice: a U-100 barrel reads units of volume. Calling them "doses" is how the confusion starts.
Correction: that gives 5 units, not what you have written. 30mg into 1mL is 30mg/mL and the division follows from there.
What concentration did you actually reconstitute at, rather than what did you intend to?
That only works if the fill weight is exactly the label weight, and it usually is not exactly anything.
reconstituting at a round concentration makes every later dose easy
reconstituting at a round concentration makes every later dose easy
emil_wojcik has the units point exactly right. They are a volume on the barrel and nothing else.
Agreed — units are volume. Once that lands, the rest of the arithmetic is one division.
Reminder: this board does maths, not dosing. Nobody here tells another member what amount to take.
Same. I got this wrong once, caught it because the units looked absurd, and have written on every vial since.
twice as much water halves the concentration and doubles the units for the same dose
Disagree with the "more water is safer" framing. It is not safer, it is just a different number to divide by.
Agreed on the swirl. There is no reason to shake it and a good reason not to.
Cosigning the round-number approach. Reconstituting to something awkward is how you end up drawing 27.5 units at six in the morning.
Not quite. Bacteriostatic and sterile water are not interchangeable for a multi-draw vial, and the difference is the preservative.
- 1Pushback on the syringe advice: a U-100 barrel reads units of volume.…7 comments in this branch · started by u/santiago_ndiaye