SP Bacteriostatic Water for Injection is sterile, non-pyrogenic water that contains 0.9% benzyl alcohol (9mg/mL) added as a bacteriostatic preservative. This preparation of sterile water and benzyl alcohol (BnOH) allows repeated withdrawals to be made from a single 10mL vial. We advise that once a vial of bacteriostatic water is open, the preservatives will prolong its life for up to 28 days. After this period, the vial should be discarded.
The difference between bacteriostatic water and sterile water is that other sterile waters for injection do not contain a bacteriostatic agent. As such, they are single-dose vials and should be discarded after a single-use.
A bacteriostatic agent or bacteriostat is a biological or chemical agent that stops bacteria from reproducing, while not necessarily killing them otherwise. Depending on their application, bacteriostatic antibiotics, disinfectants, antiseptics and preservatives can be distinguished. When bacteriostatic antimicrobials are used, the duration of therapy must be sufficient to allow host defence mechanisms to eradicate the bacteria. Upon removal of the bacteriostat, the bacteria usually start to grow again. This is in contrast to bactericides, which kill bacteria.
How to Mix medications with Bacteriostatic water:
- Using an alcohol pad, wipe the rubber stopper on the first vial to decrease the risk of contaminating the medication as you insert the needle into the vial.
- Pull back syringe plunger until the volume of air drawn into the syringe equals the volume to be withdrawn from the drug vial.
- Without inverting the vial, insert the needle into the top of the vial, making sure that the needle's bevel tip doesn't touch the solution. Inject the air into the vial and withdraw the needle. This step replaces air in the vial, thus preventing the creation of a partial vacuum on the withdrawal of the drug.
- With a new needle, repeat the step above for the second vial or empty mixing vial. Then, after injecting the air into the second vial, invert the vial, withdraw the prescribed dose, and then withdraw the needle (as shown below).
- Wipe the rubber stopper of the first vial again and insert the needle, taking care not to depress the plunger. Invert the vial, withdraw the prescribed dose, and then withdraw the needle.
- Change the needle on the syringe, if indicated.
- Last, discard all waste in appropriate sharps container of waste receptacle.