Plain sterile water is perfect for single use, but every time a needle goes through the stopper there is a chance of introducing microorganisms. Benzyl alcohol does not sterilise; it stops bacteria from multiplying, which is why the water is called “bacteriostatic” rather than “bactericidal”.
It is a widely used preservative in multi-dose parenteral preparations. Its usual concentration, 0.9% (9 mg per millilitre), is designed to be effective as a preservative without affecting most dissolved compounds.
There are cases where it is not suitable: some sensitive peptides or proteins can aggregate in its presence, and in certain clinical contexts, such as newborns, it is avoided. In those cases preservative-free sterile water is used and single-use vials are worked with.
The preservative does not replace aseptic technique or refrigeration: it only adds a safety margin for vials used repeatedly.
Related terms
Learn it in depth at the Peptide University
- Lyophilization and excipients · Module 11
- The lyophilized form and its diluents · Module 8
- Technical fundamentals of subcutaneous administration · Module 8
- Reconstitution and aseptic technique · Module 9
Related catalogue compounds
Definition for educational and scientific purposes. It is not medical advice or a recommendation for use. NeoPeptidos products are sold labelled for research use only (RUO).