Reconstitution Water
The sterile liquid — typically bacteriostatic water or sterile water for injection — used to dissolve a lyophilized (freeze-dried) peptide powder into solution for administration.
Lyophilized peptides arrive as dry powder and must be reconstituted before use. The choice of reconstitution liquid matters: bacteriostatic water (sterile water containing 0.9% benzyl alcohol) is preferred for multi-dose vials because the preservative inhibits bacterial growth and extends usable shelf life to several weeks when refrigerated. Plain sterile water for injection offers no antimicrobial protection and is appropriate only for single-use reconstitution.
The volume of water added determines the final concentration — adding 1 mL to a 5 mg vial yields a concentration of 5 mg/mL (5000 mcg/mL), while adding 2 mL yields 2.5 mg/mL. Accurate reconstitution math is critical for precise dosing, especially for compounds dosed in micrograms. Reconstituted peptides should be stored refrigerated (2–8°C) and never frozen, as freezing can degrade the peptide structure.