BAC Water is a USP-defined sterile aqueous diluent for injection containing benzyl alcohol as a bacteriostatic preservative. Unlike every other compound in this catalogue, BAC Water is a supply item, not a research compound — its purpose is to dissolve and stabilise the peptides researchers are studying. This monograph covers the USP-defined formulation, the role of benzyl alcohol, the specific neonatal contraindication, and what to look for on a quality-grade product.
Composition.
BAC Water, USP is sterile non-pyrogenic water containing 0.9% (9 mg/mL) benzyl alcohol as the preservative (some manufacturers' preparations contain 9 mg/mL or 11 mg/mL). The benzyl alcohol concentration is the defining feature — it is what distinguishes BAC Water from preservative-free Sterile Water for Injection and is the reason BAC Water tolerates multi-dose use where Sterile Water does not.
Mechanism (preservation rather than pharmacology).
Benzyl alcohol is bacteriostatic — it inhibits growth of gram-positive and gram-negative bacteria and yeasts at the 0.9% concentration used in BAC Water. The mechanism is membrane-perturbation at the preservative-relevant concentration; benzyl alcohol's longer-term clinical safety profile is well-characterised in the registered pharmaceutical record. There is no pharmacological "therapeutic effect" of BAC Water itself — the diluent is biologically inert by intent.
Safety considerations specific to BAC Water.
The single largest safety consideration is neonatal contraindication. Benzyl alcohol has been associated with toxicity in neonates (the historical "gasping syndrome"), and the FDA-approved package insert is explicit that for medications used in neonates, only preservative-free Sterile Water for Injection should be used as the diluent, not BAC Water. Researchers working in neonatal models or with research subjects in the neonatal age range should select preservative-free water rather than BAC Water.
Research context.
BAC Water is supplied at pharmaceutical-grade quality (USP) by major sterile-injectable manufacturers. Researchers should treat it as a defined USP-grade pharmaceutical product, not a research consumable to be sourced informally.
Storage and handling.
Sealed BAC Water vials are stable at controlled room temperature for the labelled shelf life. Discard any vial showing visible particulate or discolouration.
Quality and COA considerations.
A meaningful COA / package insert for BAC Water should confirm USP-grade designation, benzyl alcohol concentration (0.9% / 9 mg/mL is the standard), sterility per USP 71, pyrogen / endotoxin per USP 85, and absence of particulate. Major manufacturers' BAC Water carries straightforward FDA-approved labelling; researchers should source from USP-grade sterile-injectable manufacturers rather than research-only suppliers without USP designation.
Research-use note: This monograph is an educational summary of the USP-defined formulation and BAC Water. The product is FDA-approved as a USP-grade pharmaceutical diluent and carries a specific neonatal contraindication due to benzyl alcohol toxicity in this population. Nothing here is medical advice or a usage recommendation.
