Reconstitution is the process of adding a solvent — typically bacteriostatic water — to a lyophilized (freeze-dried) peptide to create a solution. The resulting concentration depends on two factors: the total peptide mass in the vial and the volume of solvent added.

The Formula

Concentration (mg/mL) = Peptide Amount (mg) ÷ Water Volume (mL)

For example, adding 2 mL of bacteriostatic water to a 10 mg vial yields a concentration of 5 mg/mL. On a standard 100-unit insulin syringe, each tick mark would then represent 0.05 mg (50 mcg).

Important Considerations

• Always direct the solvent stream against the glass wall of the vial — never directly onto the lyophilized cake
• Gently swirl the vial to dissolve. Do not shake vigorously, as this may damage peptide structure
• Once reconstituted, store the solution refrigerated at 2–8°C and use within the timeframe specified by the manufacturer
• Bacteriostatic water contains 0.9% benzyl alcohol as a preservative. Sterile water may be used for single-use applications