Bacteriostatic water for injection is sterile, non-pyrogenic water that contains 0.9% benzyl alcohol (9mg/ml). The alcohol is added to the water as a bacteriostatic preservative. Bacteriostatic water is used to dilute or dissolve medications that will be used for intravenous, intramuscular or subcutaneous injections.
When prepared in this way (a mixture of sterile water and benzyl alcohol), bacteriostatic water allows for multiple withdrawals from a single 30ml plastic vial within the 28 days following its first use. The addition of the benzyl alcohol suppresses or stops the growth of bacteria that could potentially contaminate humans.
Although bacteriostatic water does not interact with most drugs, a doctor should be consulted for advice on which drugs are incompatible with bacteriostatic water for injection.
Bacteriostatic water is rarely associated with adverse side effects. Side effects may occur due to contamination of bacteriostatic water, the existence of particulate matter or in connection with the drug that it is being used to dissolve. Possible side effects include fever, abscess formation, phlebitis, infections, venous thrombosis or tissue death.
Bacteriostatic water should not be used for epidural or spinal procedures. The use of bacteriostatic water in neonatal patients should be avoided as its side effects for paediatric use are not documented.
Once a vial of bacteriostatic water is open, it must be used within the next 28 days. After 28 days the preservatives added to the water no longer maintain its quality and the vial should be disposed of.