Bacteriostatic water for injection (BWFI) is USP-grade sterile water containing 0.9% w/v benzyl alcohol as a bacteriostatic preservative. The benzyl alcohol provides antimicrobial activity against most common bacterial and fungal contaminants, allowing multi-dose vial use for up to 28 days after initial puncture (per USP <797> guidelines). Storage: unopened vials are room temperature stable; after opening, store at controlled room temperature (20-25°C) or refrigerate. Available in 10mL, 20mL, and 30mL vials. ALTERNATIVES: (1) Sterile water for injection (SWFI) — no preservative, single-use only, must discard after 24 hours. Used when benzyl alcohol sensitivity exists. (2) 0.9% sodium chloride (normal saline) — some peptides (particularly HCG and certain GLP-1 agonists) specify saline as diluent. (3) Acetic acid solution — rarely required, typically only for specific research peptides that are poorly soluble at neutral pH. Always check peptide-specific reconstitution instructions. CAUTION: Benzyl alcohol is contraindicated in neonates and premature infants (gasping syndrome). Not a concern for adult use at these concentrations.
reconstitution
Bacteriostatic Water (BAC Water) — What It Is and Why It Matters
💡 Tips
Buy BAC water from reputable sources — compounding pharmacies, medical suppliers, or trusted peptide vendors. Do NOT attempt to make your own. Each BAC water vial should be discarded 28 days after first puncture regardless of remaining volume. If your BAC water looks cloudy or has particulates, discard it. Keep a fresh BAC water vial on hand — running out mid-cycle is annoying. The standard 10mL vial of BAC water is enough to reconstitute 5 typical peptide vials.
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