Bacteriostatic water serves as a common diluent for various medications. There is often confusion surrounding its proper storage, particularly regarding whether refrigeration is necessary to maintain its effectiveness and safety. Understanding the specific properties of bacteriostatic water helps clarify these storage guidelines.
Understanding Bacteriostatic Water
Bacteriostatic water is a sterile, non-pyrogenic preparation of water designed for injection, containing 0.9% benzyl alcohol. This benzyl alcohol acts as a bacteriostatic preservative, inhibiting the growth and reproduction of most bacteria. This property allows the solution to be used as a multi-dose diluent, enabling repeated withdrawals from the same vial without immediate contamination.
Its purpose is to dilute or dissolve powdered medications, such as certain hormones or peptides, into a liquid form suitable for injection. It helps ensure the medication remains sterile and effective, unlike plain sterile water which lacks this preservative. It is important to remember that this water is not for direct injection without a dissolved medication.
Refrigeration and Stability
Unopened vials of bacteriostatic water generally do not require refrigeration and are stable at typical room temperatures, usually between 15°C and 30°C (59°F and 86°F), until their expiration date. The benzyl alcohol prevents bacterial growth at these temperatures, maintaining the product’s integrity. Storing unopened vials in a cool, dark place, away from extreme heat or cold, extends the shelf life, which can be up to two to three years from the manufacturing date.
Once opened or punctured, refrigeration of bacteriostatic water is often not strictly required. While refrigeration (2-8°C or 36-46°F) can help maintain sterility and extend shelf life, it is not universally mandated if the product is used within the recommended timeframe. Always consult manufacturers’ instructions for precise storage recommendations for the specific product and the medication being reconstituted.
Maintaining Potency and Safety
The shelf life of an opened vial of bacteriostatic water is generally 28 days after the initial puncture. This 28-day rule is a widely accepted guideline, though it can vary slightly based on manufacturer recommendations and the specific drug it is mixed with. After this period, the benzyl alcohol’s effectiveness as a preservative may diminish, increasing the risk of bacterial growth and potential contamination.
Proper storage includes other environmental factors beyond temperature control. Vials should be kept in their original container, protected from direct light, which can degrade the benzyl alcohol, and away from excessive humidity. Freezing bacteriostatic water should be avoided, as it can compromise the solution’s sterile integrity. Always check the expiration date before use, and discard any vials opened longer than recommended or showing signs of cloudiness, discoloration, or particles.