Bacteriostatic water (BAC water) is a sterile water for injection. It contains about 0.9% benzyl alcohol, a bacteriostatic preservative that inhibits bacterial growth. Its primary purpose is to dilute medications for injection.
Understanding Unopened BAC Water Storage
Unopened vials of bacteriostatic water generally do not require refrigeration. Store them in a cool, dry place, away from direct sunlight, excessive heat, and freezing temperatures to maintain their stability. The ideal temperature range for storage is often specified between 60°F and 80°F (15°C to 25°C). When stored appropriately, an unopened vial can maintain its integrity for two to three years, as indicated by the expiration date on the packaging.
Understanding Opened BAC Water Storage
Once a vial of bacteriostatic water has been opened, its storage requirements change due to potential exposure to contaminants. While benzyl alcohol prevents bacterial growth, refrigeration is recommended after opening to help maintain the solution’s integrity and extend its usability. Ideally, opened bacteriostatic water should be stored in a refrigerator at temperatures between 36°F and 46°F (2°C to 8°C).
The presence of benzyl alcohol allows for multiple withdrawals from the same vial, but its effectiveness as a preservative diminishes over time once the seal is broken. For this reason, a widely accepted guideline, known as the “28-day rule,” advises discarding opened multi-dose vials of bacteriostatic water after 28 days, regardless of refrigeration. This rule exists to minimize the risk of bacterial contamination and ensure the bacteriostatic agent’s continued efficacy. It is helpful to mark the date of first use directly on the vial to track its 28-day lifespan.
Why Proper Storage is Important
Adhering to proper storage guidelines for bacteriostatic water is important for maintaining its sterility and the effectiveness of the medications it dilutes. The benzyl alcohol allows for safe multiple uses from a single vial. Without correct storage practices, such as exposure to extreme temperatures or prolonged light, the stability of the water or the preservative can be compromised.
Degradation of the benzyl alcohol or contamination of the water can lead to bacterial growth within the vial, despite its initial bacteriostatic properties. Using bacteriostatic water that has been improperly stored or has exceeded its recommended use-by date can introduce bacteria into the diluted medication. This could potentially affect the safety and therapeutic outcomes of the administered drugs, posing risks to the patient. Therefore, careful attention to storage ensures the solution remains suitable for its intended medical purposes.