Preparation / Diluent

Bacteriostatic Water

The reconstitution medium for the range — sterile water preserved with benzyl alcohol.

Research domain: Preparation
Presentation: 10 mL / vial
Assayed purity: Sterile, non-pyrogenic
Evidence base: Established

Also designatedBacteriostatic water for injection · BAC water · Sterile water for injection · Diluent

Quick facts

Purity specification: Sterile, non-pyrogenic
Physical form: Clear colourless solution
Presentation: 10 mL / vial
Evidence base: Established
Intended use: Laboratory research only

Enquire Now

Research overview

How it is characterised

Bacteriostatic water is sterile water for injection containing benzyl alcohol as a bacteriostatic preservative, which is what allows a vial to be entered more than once without the contamination risk that attends unpreserved water. It is the standard diluent for the lyophilised range, and it is supplied to the same analytical and cold-chain standard as the compounds it is used to prepare.

Mechanism

The benzyl alcohol content is bacteriostatic rather than bactericidal: it inhibits microbial growth in the vial between entries. It is not an active compound and it has no pharmacology of its own in this context. Compatibility is the property that matters, and it is stated per compound on the certificate of analysis.

Applications

Reconstitution of lyophilised material
Serial dilution preparation
Solution stability characterisation
Multi-entry vial handling

Research focus

Areas of published investigation

The following describe where this compound has been examined in the scientific literature. They are not claims of effect, and nothing here should be read as a therapeutic indication.

01Diluent compatibility

02Reconstituted solution stability

03Preservative efficacy over multiple entries

04pH and osmolality of prepared solutions

Research compatibility

Frequently co-studied

Compounds that appear alongside Bacteriostatic Water in the published record, and the reason the literature examines them together.

Molecular & pharmacokinetic data

The physical record

Verify every figure against the certificate of analysis for the batch you hold. Where the label and the assay disagree, the assay is the number to calculate from.

CAS number: 7732-18-5 (water) / 100-51-6 (benzyl alcohol)
Molecular formula: H₂O with 0.9% benzyl alcohol
Molar mass: ≈ 18.02 g/mol (water)
Solubility: Miscible; the diluent for the range

Storage

Store at controlled room temperature, protected from light. Do not freeze. Once entered, hold at 2–8 °C and observe the in-use interval stated on the certificate of analysis.

Handling

Swab the closure before each entry. Introduce the diluent slowly against the vial wall of the compound being prepared rather than directly onto the cake, and swirl rather than shake. Discard if the solution is not clear and colourless.

Packaging

Clear borosilicate vial with butyl stopper and aluminium crimp seal, presented in the matte debossed box used across the range.

Reconstitution guide

Selected references

The published record

A starting point rather than a survey. Entries are listed for orientation and do not constitute endorsement of any interpretation drawn from them.

01Benzyl alcohol as a pharmaceutical preservativeJournal of Pharmaceutical Sciences, 2011
02Reconstitution and stability of lyophilised peptidesInternational Journal of Pharmaceutics, 2016
03Preservative efficacy in multi-dose parenteral containersPDA Journal of Pharmaceutical Science and Technology, 2018