Bacteriostatic Water

Bacteriostatic Water for research handling in Thailand

Bacteriostatic water is sterile water containing a small amount of an antimicrobial preservative — typically benzyl alcohol at around 0.9% — which suppresses the growth of bacteria that would otherwise colonise a vial once its stopper has been pierced. It is the standard diluent used in laboratories to reconstitute lyophilised research peptides, because a single vial can be drawn from repeatedly over a period of weeks rather than discarded after one use.

This listing is for laboratory research use only. Bacteriostatic water supplied here is not a medicine and is not intended for human or veterinary use, and this page does not provide preparation, reconstitution, or administration instructions.

Quick facts

Product

Bacteriostatic Water (preserved research diluent)

Base component

Water (CAS 7732-18-5; H₂O)

Preservative

Benzyl alcohol (CAS 100-51-6)

Presentation

10 ml sealed multi-dose vial, single vials or multi-vial packs

Sterility

Supplied sterile and sealed; sterility depends on aseptic technique once punctured

Intended use

Laboratory research use only

How bacteriostatic water works

Benzyl alcohol is a broad-spectrum antimicrobial preservative that disrupts bacterial membrane integrity at the concentrations used in injectable formulations. It is bacteriostatic rather than bactericidal in this context: it does not sterilise a contaminated solution, it inhibits the multiplication of organisms introduced in small numbers during handling. That distinction matters — the preservative is a margin of safety around good aseptic technique, not a replacement for it.

This is the practical difference from sterile water for injection, which contains no preservative. Preservative-free sterile water is intended for single use, because any organism introduced when the stopper is pierced can proliferate freely in the vial. A preserved vial is designed to tolerate repeated withdrawals, which is why multi-draw laboratory workflows and dilution series are built around bacteriostatic water. The preservative is not inert with respect to the dissolved protein, however: benzyl alcohol has been shown to promote aggregation in some reconstituted lyophilised protein formulations, with the extent depending on how well structure was preserved during freeze-drying (Roy, J Pharm Sci, 2005).

Research applications

• Reconstituting lyophilised research peptides in laboratory preparation workflows
• Multi-draw workflows where a single vial is sampled repeatedly over several weeks
• Preparing dilution series and working stocks at defined concentrations
• Bench-side comparisons of preserved versus preservative-free diluents
• Stability and aggregation studies on reconstituted peptide formulations
• General laboratory dilution work where preservative-free water would be discarded after one use

Handling & storage

Technique

Sterile technique throughout; the preservative supplements aseptic handling, it does not replace it

Stopper

Swab the rubber stopper with alcohol and allow it to dry before each puncture

After puncture

Commonly discarded ~28 days after the first puncture, per standard multi-dose vial practice

Temperature

Room temperature storage; refrigeration is not normally required

Light

Keep sealed in the original carton and protected from direct sunlight

Discard if

The solution is cloudy, discoloured, or shows any visible particulate matter

Compatibility

Not suitable for every formulation — some drug products are documented as incompatible with benzyl-alcohol-preserved water

In Thailand's heat and humidity, "room temperature" is the point worth watching: keep vials out of parked vehicles, direct sun, and unconditioned storage rooms, and minimise time at ambient temperature during courier handling. Heat does not defeat the preservative, but it accelerates degradation of whatever has been dissolved in the water.

Selected reference

• The gasping syndrome and benzyl alcohol poisoning — New England Journal of Medicine, 1982. The report that established why benzyl alcohol preserved products are contraindicated in neonates: accumulated benzyl alcohol exposure in premature infants was associated with metabolic acidosis, gasping respiration, and death. Benzyl-alcohol-preserved diluents have carried a neonatal contraindication ever since.
• Effects of benzyl alcohol on aggregation of recombinant human interleukin-1-receptor antagonist in reconstituted lyophilized formulations — Journal of Pharmaceutical Sciences, 2005. Demonstrates that benzyl alcohol can promote protein aggregation on reconstitution, and that the effect depends on how well protein structure survived freeze-drying.
• Browse all indexed benzyl alcohol preservative literature on PubMed

Related products

• BPC-157 — a lyophilised pentadecapeptide studied in tissue-repair models; supplied as a powder requiring a diluent.
• TB-500 — synthetic Thymosin Beta-4 fragment, frequently studied alongside BPC-157 and likewise supplied lyophilised.
• Retatrutide — triple-agonist research peptide; multi-week study designs make preserved diluent the practical choice over single-use water.
• Semaglutide — GLP-1 research peptide commonly ordered together with a diluent.

See also: more research accessories.

Bacteriostatic Water FAQ

Compliance note

Bacteriostatic Water is supplied for laboratory research use only. It is not for human or veterinary use, and it is not intended to diagnose, treat, cure, or prevent any disease. The references cited above are the findings of specific published studies and the general pharmaceutical literature on benzyl alcohol as a preservative, not claims about this product.