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Bacteriostatic water for peptides
Bacteriostatic water is sterile water with 0.9% benzyl alcohol added as a preservative. It is sold in multiple-dose vials and is used to dissolve or dilute medicines for injection. It is the water most peptide vials are mixed with, because the vial is drawn from more than once.
What is bacteriostatic water
The label describes it as a sterile, nonpyrogenic preparation of water for injection that contains 0.9% (9 mg/mL) of benzyl alcohol as a bacteriostatic preservative, supplied in a multiple-dose container. [1]
"Bacteriostatic" means the preservative holds back the growth of bacteria. It does not make a dirty vial clean. The rubber top is still wiped before every draw, and every draw uses a new needle and syringe. [2]
It is a diluent. The label says it is for diluting or dissolving drugs for injection, and it is not given on its own. [1]
Bacteriostatic water vs sterile water
| Bacteriostatic water | Sterile water for injection | |
|---|---|---|
| Preservative | 0.9% benzyl alcohol | None |
| Container | Multiple-dose vial | Single-dose |
| Used when | The mixed vial will be drawn from more than once | Everything is used in one go |
Where a product has a label, the label names the diluent. Use that one.
How much bacteriostatic water to add to a peptide
There is no single right amount. The water does not change how much peptide is in the vial. It changes how much liquid each dose takes up.
| Vial | 1 mL of water | 2 mL of water | 3 mL of water |
|---|---|---|---|
| 5 mg | 5 mg/mL | 2.5 mg/mL | 1.67 mg/mL |
| 10 mg | 10 mg/mL | 5 mg/mL | 3.33 mg/mL |
| 30 mg | 30 mg/mL | 15 mg/mL | 10 mg/mL |
Pick the amount that puts your dose on a line you can read. The peptide calculator has a mode that starts from the syringe mark you want and gives the water. The mixing steps are in how to reconstitute peptides.
Storing it, and how long an opened vial is kept
The label gives room temperature for the unopened vial: 20 to 25°C (68 to 77°F). [1]
Once a multi-dose vial has been punctured, the rule used in healthcare is to write the date on it and throw it out within 28 days, unless the maker states a different date for the opened vial. That date never runs past the expiry printed on the vial. [2]
Who it is not for
The label carries a warning that benzyl alcohol has been associated with toxicity in newborns, and that solutions containing it must not be used in neonates. [1]
It also says products with benzyl alcohol should not be used for fluid replacement. [1]
Questions
What is bacteriostatic water used for?
Diluting or dissolving medicines for injection. It contains 0.9% benzyl alcohol as a preservative and comes in a multiple-dose vial.
Can I use sterile water instead of bacteriostatic water for peptides?
Sterile water has no preservative and is meant for a single use. Bacteriostatic water is used when the mixed vial will be drawn from more than once. Follow the label where there is one.
How long is bacteriostatic water good for after opening?
The healthcare rule for a punctured multi-dose vial is 28 days, unless the maker gives a different date.
Does bacteriostatic water need to be refrigerated?
The label for the unopened vial gives room temperature, 20 to 25 degrees C.
How much bacteriostatic water for a 10 mg peptide vial?
Any measured amount. 2 mL gives 5 mg/mL and 1 mL gives 10 mg/mL.
Sources
- Bacteriostatic Water for Injection, USP. Prescribing information, Hospira. DailyMed, US National Library of Medicine. dailymed.nlm.nih.gov.
- Preventing Unsafe Injection Practices. US Centers for Disease Control and Prevention. cdc.gov.
Related
How to reconstitute peptidesHow to store peptidesPeptide calculatorPeptide dosage chartDosages A to ZAll guides
DosageFacts is an information site. It is not medical advice. Talk to a licensed professional before using any medication.