Bacteriostatic Water for Injection is sterile, non-pyrogenic water that contains 0.9% benzyl alcohol (9mg/mL) added as a bacteriostatic preservative. This preparation of sterile water and benzyl alcohol (BnOH) allows repeated withdrawals to be made from a single vial. Hospira, the world’s leading manufacturer and supplier of bacteriostatic and sterile water, advises that once a vial of bacteriostatic water is open, the preservatives will prolong its life for up to 28 days. After this period, the vial should be discarded.
The difference between bacteriostatic water and sterile water is that other sterile waters for injection do not contain a bacteriostatic agent. As such, they are single-dose vials and should be discarded after a single use.