Bacteriostatic water is sterile water containing a bacteriostatic agent, typically 0.9% benzyl alcohol. This additive inhibits bacterial growth, distinguishing it from plain sterile water. Its primary purpose is to dilute or dissolve injectable medications, allowing for multiple withdrawals from the same vial without immediate contamination concerns, making it common in medical settings.
Does Refrigeration Matter?
Bacteriostatic water does not require refrigeration. The benzyl alcohol effectively inhibits bacterial growth at controlled room temperatures, making refrigeration unnecessary for maintaining sterility or efficacy. While refrigeration does not harm the water, it provides no additional preservation benefits, as the benzyl alcohol remains stable without cold storage.
However, if bacteriostatic water is mixed with certain medications, refrigeration might be recommended based on the specific drug’s stability. Colder temperatures can cause some dissolved substances to precipitate out of the solution. This concern relates more to the mixed medication’s stability than to the bacteriostatic water itself. Always consult the medication’s instructions for storage guidelines after reconstitution.
Proper Storage Practices
Optimal storage conditions for bacteriostatic water involve keeping it at a controlled room temperature, typically between 20 to 25°C (68 to 77°F). Maintaining a consistent temperature within this range helps preserve the integrity of the solution and the effectiveness of the benzyl alcohol. Exposure to extreme temperatures, such as excessive heat or freezing, should be avoided as it can compromise the water’s sterile properties or the preservative’s stability.
It is important to store bacteriostatic water in its original container, away from direct sunlight or other sources of light. Prolonged light exposure can degrade the benzyl alcohol, diminishing its ability to prevent bacterial growth. Ensuring the container is tightly sealed when not in use also prevents the introduction of airborne contaminants like bacteria or dust particles. For safety, always store bacteriostatic water out of the reach of children.
Understanding Shelf Life
Bacteriostatic water has two primary aspects to its shelf life: the expiration date on the unopened vial and an “in-use” expiration period once punctured. Unopened vials have a shelf life of two to three years from the manufacturing date, indicated by the printed expiration date. This date guarantees the product’s stability and sterility before initial use.
Once a vial of bacteriostatic water has been punctured, a common guideline, often referred to as the “28-day rule,” applies. This rule advises discarding the vial within 28 days of the first use, even if some liquid remains. The 28-day limit ensures the continued efficacy of the benzyl alcohol preservative against potential microbial contamination introduced during repeated withdrawals. Before each use, visually inspect the water for any discoloration, cloudiness, or particulate matter, which could indicate contamination or degradation, and discard if such signs are present.