Description
Summary Abstract
Bacteriostatic Water for Injection (Water for Injection with 0.9% w/v benzyl alcohol; USP/BP grade; pH 5.7; sterile-filtered; 10 mL multi-dose vial) is the standard pharmaceutical-grade reconstitution medium for lyophilized peptides and protein-based research compounds. Benzyl alcohol at the 0.9% concentration (9 mg/mL) inhibits microbial proliferation in the reconstituted vial across repeated-puncture cycles, permitting multi-dose protocols over a 28-day beyond-use date (BUD) per USP Chapter <797> sterile compounding guidance. The slightly acidic pH (~5.7) and near-isotonic osmolarity (~300 mOsm/L) are compatible with the overwhelming majority of synthetic peptides in lyophilized form and do not disrupt peptide backbone integrity at standard research concentrations. A 10 mL vial provides sufficient solvent for multiple individual peptide vial reconstitutions, minimizing solvent waste and reducing per-dose preparation overhead in high-throughput research workflows.
Clinical Indications
Bacteriostatic water serves as an essential reconstitution medium and diluent in the following research and clinical compounding contexts:
- Lyophilized Peptide Reconstitution: The primary use case — dissolving freeze-dried synthetic peptides (including growth hormone secretagogues, repair peptides, and anti-inflammatory tripeptides) into a stable injectable solution at a defined, precise concentration.
- Multi-Dose Protocol Support: The benzyl alcohol preservative permits 28-day multi-dose vial use after first puncture, enabling high-frequency sampling protocols without daily solvent preparation.
- Protein and Biologic Dilution: Used as a diluent for other parenteral formulations requiring aqueous vehicle addition prior to administration, per FDA-labeled multi-dose container applications.
Contraindications
- Neonatal Use: The FDA label for bacteriostatic water explicitly contraindicates benzyl alcohol-containing preparations in neonates due to documented benzyl alcohol toxicity (gasping syndrome) in premature and low-birth-weight infants; preservative-free sterile water for injection must be used in this population.
- Epidural or Intrathecal Injection: Benzyl alcohol is neurotoxic via direct CNS contact; bacteriostatic water is contraindicated for epidural or spinal anesthesia procedures.
- Benzyl Alcohol-Sensitive Peptides: A small subset of synthetic peptides (e.g., oxytocin, vasopressin, desmopressin) exhibit stability degradation in the presence of benzyl alcohol; sterile water for injection should be used for these compounds.
- Intravenous Bolus Without Isotonicity Adjustment: Per USP labeling, bacteriostatic water must not be used for IV injection unless the osmolarity of added solutes achieves approximate isotonicity.
Mechanism of Action (MOA)
Bacteriostatic water functions through two concurrent modes of action — antimicrobial preservation and physicochemical peptide stabilization:
Benzyl Alcohol Bacteriostatic Preservation
Benzyl alcohol (0.9% w/v; 9 mg/mL) inhibits microbial replication by disrupting bacterial cell membrane integrity and interfering with membrane-dependent enzymatic processes. The mechanism is bacteriostatic rather than bactericidal — organisms are prevented from proliferating rather than being killed outright — providing sufficient microbial control for multi-dose vial use over a 28-day period under standard storage conditions per USP <797>.
Physicochemical Peptide Stabilization
The mildly acidic pH (4.5–7.0; nominal 5.7) of bacteriostatic water suppresses oxidative degradation pathways that accelerate under alkaline conditions. The near-isotonic osmolarity (~300 mOsm/L) minimizes osmotic stress on reconstituted biological molecules. Unlike reactive solvents, benzyl alcohol at 0.9% does not form covalent adducts with standard peptide backbones at typical working concentrations, preserving molecular integrity throughout multi-dose storage windows.
Multi-Dose Vial Sterility Maintenance
Following the first stopper puncture, each subsequent needle entry introduces a small risk of microbial contamination. Benzyl alcohol’s bacteriostatic activity provides a continuous antimicrobial buffer that suppresses this risk across repeated draws, enabling the 28-day multi-dose protocol. USP Chapter <797> formalizes this window as the recognized beyond-use date for multi-dose preserved sterile injectable containers.
Key Features & Specifications
Defining properties of this 10 mL multi-dose bacteriostatic water vial:
Chemical Analysis
| Property | Specification Reference Data |
|---|---|
| Composition | Water for Injection, USP + 0.9% w/v Benzyl Alcohol (9 mg/mL) |
| Benzyl Alcohol CAS | 100-51-6 |
| Benzyl Alcohol Formula | C7H8O (MW 108.14 g/mol) |
| pH | 5.7 (acceptable range: 4.5–7.0) |
| Osmolarity | ~300 mOsm/L (near-isotonic) |
| Sterility | Sterile-filtered; pyrogen-free; USP/BP compliant |
| Container | 10 mL multi-dose polyolefin vial with rubber stopper |
| Form / Variation | 10 mL Multi-Dose Vial (V-008) |
Storage, Safety, and Handling
Storage Protocol
Unopened vials store at controlled room temperature (20–25 °C; 68–77 °F), protected from direct light and freezing. Manufacturer shelf life is typically 18–24 months from production date. After first stopper puncture, the 28-day beyond-use date clock begins per USP <797>; label each vial with the date of first use and discard at or before the 28-day mark regardless of remaining volume or visual appearance.
Handling & Compliance
Maintain aseptic technique throughout: swab the rubber stopper with a 70% isopropyl alcohol prep pad before each needle entry and allow to fully air-dry before puncture. Inspect the solution before each draw — discard any vial showing cloudiness, discoloration, or visible particulates. Do not use benzyl alcohol-containing preparations in neonates, for epidural/intrathecal procedures, or for undiluted IV bolus administration. Handle needles and sharps per institutional waste disposal protocols.