What is reconstitution?
Peptides are typically supplied as lyophilized (freeze-dried) powder inside a sealed vial. Reconstitution refers to adding a sterile diluent — usually bacteriostatic water — to dissolve the powder into a solution that can be measured and drawn into a syringe. The amount of diluent you add directly determines the concentration (mg/mL) of the resulting solution.
How concentration works
Concentration is the relationship between the amount of peptide in the vial and the volume of diluent added:
concentration (mg/mL) = vial size (mg) ÷ diluent (mL)
For example, reconstituting a 10 mg vial with 2 mL of bacteriostatic water yields a concentration of 5 mg/mL. The same 10 mg vial reconstituted with 1 mL would yield 10 mg/mL — twice as concentrated, meaning each draw contains more peptide per unit volume.
mg to mL conversion
Once concentration is known, the volume needed to deliver a given dose is straightforward:
draw volume (mL) = dose (mg) ÷ concentration (mg/mL)
At 5 mg/mL, a 0.5 mg dose corresponds to 0.1 mL. On a U-100 insulin syringe, that's the 10-unit mark. Working in micrograms (mcg) is identical math — just remember 1 mg = 1000 mcg.
Reading a U-100 syringe
U-100 insulin syringes are calibrated so that 100 units equals 1 mL. This makes them well-suited for measuring small volumes: every 10 units represents 0.1 mL. Common sizes are 0.3 mL (30 units), 0.5 mL (50 units), and 1 mL (100 units). Choose the smallest syringe that comfortably accommodates your draw volume — smaller syringes have finer graduations and are easier to read accurately.
Why visual tools matter
Reading concentration and volume from numbers alone is error-prone. A small mistake in mental math — confusing mg with mcg, or misreading a decimal — can compound across days. A clear visual reference removes the ambiguity: you see exactly how much liquid is in the vial, exactly how much is drawn into the syringe, and exactly where the plunger should sit.