Supplies

Bacteriostatic Water

BAC Water, Bacteriostatic saline, 0.9% benzyl alcohol water

Bacteriostatic water is sterile water preserved with 0.9% benzyl alcohol that prevents bacterial growth for up to 28 days after opening — making it the standard reconstitution agent for all injectable peptides.

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This peptide profile is for research and educational purposes only. Not intended for human use or self-administration.

Overview

Bacteriostatic water (BAC water) is sterile water for injection containing 0.9% benzyl alcohol as a bacteriostatic preservative. It is the standard and recommended diluent for reconstituting lyophilized (freeze-dried) peptides, hormones, and other injectable research compounds. Unlike single-use sterile water, BAC water remains safe to use for up to 28 days after the vial is first punctured because the benzyl alcohol prevents bacterial and fungal contamination of the multi-use vial. Understanding correct reconstitution technique with BAC water is foundational to any injectable peptide research protocol.

Mechanism of Action

Benzyl alcohol (C6H5CH2OH) is a bacteriostatic agent that disrupts bacterial cell membrane function and inhibits cell growth at the 0.9% concentration used in BAC water. It does not sterilize — it prevents re-contamination after the vial seal is broken. The water itself is sterile by manufacturing process (autoclaved or filtered). When added to lyophilized peptide, BAC water dissolves the powder into a stable aqueous solution while maintaining sterility across multiple draws from the same vial. Benzyl alcohol is compatible with most peptides at standard doses. At high doses, benzyl alcohol can be directly toxic (particularly in neonates), but at the concentrations received from standard peptide reconstitution volumes, systemic exposure is negligible.

Key Research

BAC water is a pharmaceutical-grade product manufactured under USP standards. Its 0.9% benzyl alcohol concentration is the accepted standard for preserving multi-use injectable vials. Regulatory guidance from the FDA and USP establishes the 28-day discard date for opened multi-dose vials containing bacteriostatic preservatives. The 30 mL vial size is the standard for peptide reconstitution research — sufficient to reconstitute multiple vials across a cycle. Benzyl alcohol toxicity in neonates is well-documented from high-dose IV exposure; at typical reconstitution volumes (1–2 mL per peptide vial), total benzyl alcohol delivered per dose is well within safe limits for adults.

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Research Dosing

Typical Dose

N/A (diluent — dose determined by desired peptide concentration)

Half-Life

N/A

To reconstitute a lyophilized peptide vial: wipe the rubber stopper of both the BAC water vial and the peptide vial with an alcohol swab and allow to air dry. Draw the desired volume of BAC water into a sterile insulin syringe. Insert the needle at a 45-degree angle into the peptide vial and inject the BAC water slowly down the inside wall of the vial — do not spray directly onto the powder. Gently swirl or roll the vial to dissolve the powder; do not shake or vortex. Allow to sit at room temperature for 5–10 minutes if powder does not fully dissolve immediately. Standard reconstitution volumes: 1–2 mL BAC water per peptide vial yields a convenient concentration for U-100 insulin syringe dosing. Refrigerate the reconstituted vial immediately after preparation.
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Protocols

Standard Reconstitution Reference: 5 mg peptide vial + 1 mL BAC water = 5,000 mcg/mL (1 unit on U-100 syringe = 50 mcg). 5 mg + 2 mL = 2,500 mcg/mL (1 unit = 25 mcg). 5 mg + 5 mL = 1,000 mcg/mL (1 unit = 10 mcg). 2 mg + 2 mL = 1,000 mcg/mL. Adjust the BAC water volume to achieve a concentration that makes your target dose easy to draw accurately on a U-100 insulin syringe.

Reported Side Effects

Side effects summarized from animal studies and researcher community observations. Educational purposes only — not medical advice.
Bacteriostatic water is extremely well tolerated at volumes used for peptide reconstitution. Mild stinging at the injection site from the benzyl alcohol is the most commonly reported experience — this is normal and resolves quickly. If stinging is bothersome, allow the reconstituted peptide solution to come to room temperature before injecting (cold solutions sting more). Benzyl alcohol toxicity is only a concern at very high intravenous doses (typically seen in neonatal intensive care settings from repeated exposure to benzyl alcohol-preserved flushes) — not at volumes associated with peptide research. Do not use bacteriostatic water in neonates or for high-volume IV infusions.

Storage & Handling

Store BAC water at room temperature (15–25°C) before opening. Once opened, store at room temperature or in the refrigerator. Use within 28 days of first puncture per USP guidelines. Discard if solution becomes discolored, cloudy, or contains visible particles. Keep the rubber stopper clean and sterile — wipe with a fresh alcohol swab before each use. Do not contaminate the stopper with bare fingers. 10 mL and 30 mL vials are the most common sizes for peptide research.