Glossary
Plain-English definitions of the terms used across our products and guides.
- Bacteriostatic water
- Sterile water containing 0.9% (9 mg/mL) benzyl alcohol, a bacteriostatic preservative that inhibits the growth of most common bacteria. The preservative allows a sealed multi-dose vial to be accessed repeatedly. Use only as specified in the manufacturer product information and under qualified healthcare-professional direction. What is BAC water? →
- Sterile water
- Purified water that has been filtered to remove microorganisms and sealed under sterile conditions, with no preservative added. Because there is no bacteriostatic agent, a sterile water vial is intended for a single withdrawal and should not be re-entered. Bacteriostatic water vs sterile water →
- Bacteriostatic sodium chloride (saline)
- An isotonic 0.9% sodium chloride (saline) solution with benzyl alcohol added as a bacteriostatic preservative, allowing repeated access to a sealed multi-dose vial. Follow the supplied product's manufacturer information for its intended application. What is bacteriostatic sodium chloride? →
- Benzyl alcohol
- A colourless aromatic alcohol used as a preservative in certain medical solutions. At 0.9% (9 mg/mL) it acts as a bacteriostatic agent, holding bacterial growth in check after a vial's seal is broken. How the preservative works →
- Bacteriostatic
- Describes an agent that inhibits the growth and reproduction of bacteria without necessarily killing them — from the Greek stasis, a standstill. In bacteriostatic water and bacteriostatic saline, 0.9% benzyl alcohol performs this role, holding bacterial growth in check between entries into a multi-dose vial. A bacteriostatic preservative does not guarantee sterility after opening and does not replace the supplied handling requirements. How the preservative works →
- Bactericidal
- Describes an agent that kills bacteria outright, rather than merely halting their growth. The distinction matters when reading labels: the preservative in bacteriostatic water is bacteriostatic, not bactericidal, so it suppresses growth between vial entries but cannot make a contaminated solution safe.
- Reconstitution
- The process of dissolving or diluting a substance in a liquid such as bacteriostatic or sterile water. Product selection, preparation and use must follow the supplied manufacturer information under qualified healthcare-professional direction.
- Multi-dose vial
- A manufacturer-labelled vial presentation intended for more than one withdrawal when handled as specified in its product information by qualified personnel.
- In-use period
- The fixed period during which a multi-dose vial may continue to be used, running from the moment its stopper is first entered. It is separate from, and much shorter than, the expiry date printed on the sealed vial; whichever falls first ends the vial's usable life. How long does a vial last? →
- Clarity
- Freedom from visible haze, cloudiness or suspended particulate. Bacteriostatic water is expected to be a clear, colourless solution, and a departure from that appearance is treated as an inspection failure rather than a cosmetic issue. Inspecting a vial for clarity →
- Cloudiness (haze)
- The visible scattering of light by particles that are not dissolved — undissolved solid, a precipitate, aggregated material or contamination. A true solution is optically clear because dissolved molecules are too small to scatter visible light, so haze is direct evidence that something in the container is out of solution. Where material is expected to be clear and is not, it is not used. What cloudiness indicates →
- Precipitation
- The coming out of solution of a substance that was previously dissolved, appearing as haze, crystals or a deposit. It is commonly driven by a change in pH, concentration, temperature or ionic strength.
- Particulate matter
- Undissolved foreign or intrinsic material visible in a solution — flakes, fibres, crystals or fragments. Injectable presentations are released against specified particulate limits, and a vial with visible particulate is discarded rather than filtered or decanted.
- Coring
- The punching out of a fragment of a vial's rubber stopper by a needle, rather than the stopper parting cleanly, leaving the fragment in the solution. It becomes more likely with repeated entries into the same point on a stopper, which is why a multi-dose vial is inspected before every entry. What to check before use →
- Isotonic
- A solution with the same effective osmotic concentration as a reference solution. Sodium chloride 0.9% is commonly described as isotonic saline.
- Nonpyrogenic
- Free of fever-inducing substances, principally bacterial endotoxin. It is a distinct release requirement from sterility: a solution can be sterile and still contain pyrogens left behind by organisms killed during processing.
- USP monograph
- The published United States Pharmacopeia standard a compendial product is manufactured and released against, covering identity, sterility, preservative content, particulate limits, container closure integrity and a controlled pH range. Bacteriostatic Water for Injection USP is released against that specification rather than a manufacturer's private recipe. The compendial specification →
- Medical grade
- A product manufactured and labelled for medical use under the quality requirements applicable to its manufacturer presentation. Aus BAC Supply supplies original, factory-sealed manufacturer products without alteration.
Looking for the products these terms describe? We stock factory-sealed bacteriostatic water (BAC water) and bacteriostatic sodium chloride 0.9% (BAC saline), dispatched from Melbourne.
These products are diluents or solvents, not ready-to-administer medicines. Never inject by themselves or self-administer. Follow the supplied manufacturer information and qualified healthcare-professional direction.