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Let the vial reach room temperature, swab the stopper, then draw your bacteriostatic water and angle the needle so the stream runs down the inner wall of the vial rather than jetting onto the powder. Let the vacuum pull it in, then swirl gently or leave it to dissolve. Never shake it — agitation shears peptide chains. Wait until the solution is completely clear before using it.

It is a free choice, and it is the only lever you have over measurement precision. More water means a weaker solution and a larger, easier-to-read draw. A 5 mg vial in 1 mL puts a 250 mcg dose at 5 units, where half a unit of error is a 10% dosing error. The same vial in 2.5 mL puts it at 12.5 units, where the same slip matters far less. Aim for your usual dose to land in the middle of the barrel.

A unit is a volume, not an amount of peptide. On a standard U-100 syringe, 1 unit is 0.01 mL. Ten units drawn from a weak mix and ten from a strong one fill the barrel to exactly the same line, but one holds several times more peptide. That is why a calculator has to know what you put in the vial before it can tell you what to draw.

Divide the total peptide in the vial by your dose. A 5 mg vial dosed at 250 mcg gives 20 doses, because 5 mg is 5000 mcg and 5000 divided by 250 is 20. The amount of water you add does not change how many doses you get — only how much liquid each one is.

Lyophilised powder kept sealed at −20 °C is generally stable for a year or more. Once reconstituted with bacteriostatic water and refrigerated at 2–8 °C, most compounds are considered usable for roughly two to four weeks, though this varies. Sterile water without preservative is much shorter, usually a single session. Never freeze a reconstituted vial.

A milligram is 1000 micrograms. An international unit is different again — it measures biological activity rather than mass, and the conversion to milligrams is specific to each compound, so there is no universal factor. Syringe units are a fourth thing entirely: pure volume, at 0.01 mL each.