Sterile water for injection containing 0.9% benzyl alcohol as preservative. Standard reconstitution medium for lyophilized peptides in research settings. Preservative extends multi-use stability.
Bacteriostatic water (BAC water) is sterile water that contains a small concentration of benzyl alcohol — typically 0.9%. It is used as a diluent to reconstitute lyophilized (freeze-dried) peptides and other injectable compounds for research purposes. It is not a research compound itself but rather a preparation vehicle.
Reconstitution Use
BAC water is the standard diluent used to reconstitute lyophilized peptides for injection in research settings. The benzyl alcohol acts as a preservative, allowing the reconstituted solution to remain stable for a longer period than plain sterile water would allow — typically up to 28 days when refrigerated.
Bacteriostatic Properties
The benzyl alcohol concentration in BAC water inhibits bacterial growth, which is why it is described as bacteriostatic (it stops bacteria from multiplying) rather than sterile water, which simply lacks bacteria at the time of filling. This property extends the usable life of reconstituted preparations.
Benzyl alcohol at 0.9% effectively inhibits bacterial growth in aqueous solutions.
Reconstituted peptides in BAC water are generally stable for up to 28 days refrigerated, compared to shorter windows with sterile water.
BAC water is a standard component of research peptide reconstitution protocols.
No pharmacological activity of its own — effects come entirely from the compound being reconstituted.
BAC water is not a treatment and has no pharmacological effect on its own. The benzyl alcohol preservative is not appropriate for neonates or newborns in clinical settings, as high cumulative doses have been associated with toxicity in that population. For research purposes in adults, the small amounts used in standard reconstitution are not associated with concerns. Always use the appropriate volume to achieve the intended concentration of the active compound.
Lyophilized peptides are dried down to a powder to preserve their stability during storage. Before use, they need to be dissolved back into a liquid — a process called reconstitution. BAC water is simply a clean, sterile water solution with a small amount of benzyl alcohol added as a preservative. The benzyl alcohol does not kill bacteria outright but prevents them from multiplying, which helps keep the solution safe for repeated use from the same vial. When you add BAC water to a peptide vial, you are simply creating an injectable solution of the peptide at a specific concentration based on how much water you add.
BAC water itself is well-characterized and widely used in pharmaceutical and research settings. The primary safety consideration in peptide research is the sterility and quality of the reconstitution process, not the BAC water itself. Using inappropriate diluents, non-sterile water, or incorrect volumes can introduce contamination or result in incorrect dosing. BAC water should be stored appropriately and discarded after the recommended period.
High Evidence
This compound has been studied in multiple large randomized controlled trials with human subjects. The evidence base is strong and consistent across independent research groups.
Published Research Ranges
Volume determined by desired concentration for reconstituted compound
Research Context Only: These are ranges reported in published scientific studies for educational reference. They are not dosing recommendations. This is not medical advice. Always consult a qualified healthcare professional.
Sources listed here are from the platform research library. All links open the original publication. No citations are generated by AI.
Bacteriostatic Water for Injection: Benzyl Alcohol Stability and Safety Profile
American Journal of Health-System Pharmacy • 1999
• DOI: 10.1093/ajhp/56.16.1636
Research Education Only: This profile is for educational purposes only. All information is sourced from published scientific literature. This is not medical advice. Not for human consumption. Consult qualified medical professionals for any health decisions.
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