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Bacteriostatic Water
BAC Water | Sterile Water with 0.9% Benzyl Alcohol | Pharmacy Diluent for Peptide Reconstitution
Aliases (5)
Overview
What is Bacteriostatic Water?
Bacteriostatic water for injection (BWFI, BAC water) is sterile water USP combined with 0.9% (9 mg/mL) benzyl alcohol as a bacteriostatic preservative. It is an FDA-approved injectable diluent used as the workhorse for reconstituting lyophilized peptides and other freeze-dried injectable medications. It is not a therapeutic compound — it is a peptide-protocol consumable.
Key Benefits
The 0.9% benzyl alcohol preservative inhibits bacterial and fungal growth, allowing the same vial to be punctured repeatedly over ~28 days without contamination — making it the standard choice for multi-dose peptide vials in biohacker, athletic, and clinical contexts. Common pack sizes 10-30 mL; common reconstitution volumes 1-10 mL per peptide vial.
Mechanism of Action
Benzyl alcohol disrupts bacterial cell membranes at the 0.9% concentration, preventing colonization between needle entries. The water itself is a neutral, hypotonic solvent that dissolves lyophilized peptide cake without altering its structure.
Quality Indicators
Clear, Colorless Solution
Solution should be crystal clear with no particles, cloudiness, or color tint. Any visible particulates = discard.
Intact Stopper Seal
Vial cap and stopper should be undamaged. Tamper-evident flip-top should be intact pre-puncture.
Pharmacy or Pharma-Grade Source
Hospira, Pfizer, Fresenius, or licensed compounding pharmacy product. Look for NDC number on label, lot number, expiration date.
Past 28 Days Post-Puncture
Multi-dose stability is rated for ~28 days after first puncture. After that, discard even if visually clear — preservative efficacy decays.
Cloudiness or Particulates
Any visible turbidity, particles, fibers, or floaters = bacterial/fungal contamination risk. Discard immediately.
Unknown / Unmarked Source
Avoid unlabeled vials, gray-market 'BAC water' from peptide vendors with no NDC or lot number, or DIY home-mixed solutions. Manufacturing impurities are the real injection risk.
What to Expect
- Week 1Tolerability and dose-response.
- Week 2-4Early effect window.
- Week 4-8Peak benefit assessment.
- Week 8+Cycle decision point.
References
FDA Label — Bacteriostatic Water for Injection USP (Hospira)
FDA-approved labeling, composition, indications, contraindications, warnings
View StudyDailyMed — Bacteriostatic Water for Injection (Pfizer/Hospira)
current FDA package insert; benzyl alcohol 0.9% as bacteriostatic preservative
View StudyGershanik et al. 1982 — The gasping syndrome and benzyl alcohol poisoning (NEJM)
PMID 7144836; original report linking benzyl alcohol-preserved IV solutions to neonatal gasping syndrome
View StudyAmerican Academy of Pediatrics 1983 — Benzyl Alcohol: Toxic Agent in Neonatal Units
PMID 6889042; AAP committee report codifying neonatal contraindication
View StudyFDA — Inactive Ingredient Database: Benzyl Alcohol
maximum permissible daily exposure thresholds for benzyl alcohol in injectables
View StudyBrazis et al. 1991 — Benzyl alcohol toxicity in adults and infants (Pharmacotherapy)
PMID 2057965; review of benzyl alcohol pharmacology
View StudyUSP General Chapter <797> — Pharmaceutical Compounding Sterile Preparations
multi-dose vial beyond-use date guidance (~28 days)
View StudyCDC — Safe Injection Practices Guidelines
multi-dose vial usage guidelines, single-patient assignment recommendations
View StudySterile Water for Injection USP — FDA Label
comparison reference; sterile water without preservative (single-dose only)
View StudyLatest research
- standardUSP General Chapter <797> — Pharmaceutical Compounding Sterile PreparationsMulti-dose vial beyond-use dates capped at ~28 days for preserved diluents; this is the standard biohacker community references when the "discard 28 days post-puncture" rule comes up.
- safety-signalAAP Committee on Drugs — Benzyl Alcohol Toxic Agent in Neonatal UnitsPMID 6889042. AAP statement codifying the neonatal contraindication; also flagged adult thresholds (~99 mg/kg/day total exposure) that are essentially impossible to reach with 0.5-5 mL/day biohacker dosing.
- safety-signalThe gasping syndrome and benzyl alcohol poisoning (NEJM)PMID 7144836. Original case-cluster report linking benzyl alcohol-preserved IV solutions to fatal gasping syndrome in low-birth-weight neonates. Established the neonatal contraindication that persists in modern FDA labeling.
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