Bacteriostatic Water vs. Sterile Water: Critical Differences
EXOMA Scientific Team · Publicado el · Actualizado el
Understand the differences between types of water for reconstitution and when to use each to maintain the stability of your peptides.
Bacteriostatic Water vs. Sterile Water for Peptide Reconstitution
The choice of diluent is critical: it affects peptide stability, contamination risk, solution shelf life and the validity of the experimental data.
Definitions
Sterile Water for Injection (SWFI)
- USP purified water, sterilized, pyrogen-free.
- Preservative-free.
- pH ~5.5–7; endotoxins <0.25 EU/mL.
Bacteriostatic Water (BAC)
- Sterile water with 0.9% benzyl alcohol as a bacteriostatic.
- Inhibits bacterial growth after multiple punctures.
- Shelf life after opening: 28 days refrigerated.
Comparison table
| Atributo | Estéril | Bacteriostática |
|---|---|---|
| Conservante | Ninguno | Alcohol bencílico 0.9% |
| Multidosis | No | Sí (≤28 días) |
| Compatibilidad pediátrica | Sí | No (contraindicada en neonatos) |
| Life of the reconstituted peptide | Horas | Hasta 28 días |
When to use sterile water
- Single-dose vials.
- Peptides known to be stable for only hours in solution.
- Protocols with a strict requirement for the absence of additives.
- Studies where the benzyl alcohol interferes with the endpoint (sensitive cultures).
When to use bacteriostatic
- Multidose vials to be used over days/weeks.
- Peptides stable in solution (BPC-157, TB-500, GHK-Cu, sermorelin, ipamorelin).
- When dose uniformity over time is required.
Common errors
- Reconstitute with sterile water and store the vial for several days.
- Using BAC on peptides sensitive to benzyl alcohol.
- Not respecting the 28-day rule after opening.
- Inyectar volumen excesivo de BAC en modelos animales.
Typical volumes
| Péptido | Cantidad | Volumen BAC | Concentración |
|---|---|---|---|
| BPC-157 | 5 mg | 2.5 mL | 2 mg/mL |
| TB-500 | 10 mg | 2 mL | 5 mg/mL |
| GHK-Cu | 50 mg | 2.5 mL | 20 mg/mL |
| Sermorelin | 10 mg | 2 mL | 5 mg/mL |
Best practices
- Clean the stopper with isopropanol before each puncture.
- Add diluent by letting it slide down the wall, not as a direct stream.
- No vigorous shaking (avoids foam formation).
- Store refrigerated (2–8 °C) in professional packaging.
- Label with reconstitution date.
References
- USP <797> Pharmaceutical Compounding — Sterile Preparations.
- FDA Guidance on Benzyl Alcohol in Multi-Dose Vials.
Technical document for scientific research.
Products available at EXOMA
See also
Literature on the compounds cited
- About Ipamorelin: Ipamorelin, the first selective growth hormone secretagogue (Raun, et al. · European Journal of Endocrinology · 1998) PMID 9849822.
- About Ipamorelin: A new series of highly potent growth hormone-releasing peptides derived from ipamorelin (Ankersen, et al. · Journal of Medicinal Chemistry · 1998) PMID 9733495.
- About BPC-157: Protective effects of pentadecapeptide BPC 157 on gastric ulcer in rats (Xue, et al. · World Journal of Gastroenterology · 2004) PMID 15052688.
- About BPC-157: Focus on ulcerative colitis: stable gastric pentadecapeptide BPC 157 (Sikiric, et al. · Current Medicinal Chemistry · 2012) PMID 22300085.
- About BPC-157: The promoting effect of pentadecapeptide BPC 157 on tendon healing involves tendon outgrowth, cell survival, and cell migration (Chang, et al. · Journal of Applied Physiology · 2011) PMID 21030672.
- About GHK-Cu: Glycyl-L-histidyl-L-lysine-Cu(2+) rescues cigarette smoking-induced skeletal muscle dysfunction via a sirtuin 1-dependent pathway (Deng, et al. · Journal of Cachexia, Sarcopenia and Muscle · 2023) PMID 36905132.