Bacteriostatic Water

Also known as: BAC water, Bacteriostatic Water for Injection USP

Category: Supplies

Sterile water with 0.9% benzyl alcohol added as a preservative. It dissolves powdered peptides so they can be injected, and the preservative keeps bacteria from growing each time the vial is used.

What it's used for

• Mixing (reconstituting) freeze-dried peptide powder before injecting
• Making one vial safe to draw from many times over several weeks

Using it

How much to add

Usually 1 to 3 mL per peptide vial. The amount does not change how much peptide is in the vial. It only changes how many units you draw for each dose. Choose an amount that makes each dose between about 5 and 50 units on a U-100 syringe. The calculator on the dosing guide does this math.

Once opened

Throw the water vial away 28 days after the first needle goes in, which is the standard for multi-dose vials.

Used with

Injectable peptides given under the skin or into muscle

Storage

Keep unopened water at room temperature and check the expiry date. Once a peptide is mixed, keep that vial in the fridge and never freeze it.

Bacteriostatic water vs. other liquids

• Bacteriostatic water has a preservative, so a mixed vial can be used for multiple doses over several weeks.
• Sterile water for injection has no preservative. Once punctured it is meant for one use, because bacteria can grow in it.
• Never use tap, bottled, distilled or boiled water. It is not sterile and can cause serious infections.
• Some peptides come with their own diluent or instructions, such as a specific solution. Follow those when they exist.

How to mix a peptide vial

1. Wash your hands and let both vials reach room temperature.
2. Wipe both rubber stoppers with an alcohol pad and let them dry.
3. Draw the amount of bacteriostatic water you need with a new syringe.
4. Insert the needle into the peptide vial at an angle, and push slowly so the water runs down the glass wall instead of spraying onto the powder.
5. Swirl or roll the vial gently until the powder dissolves. Do not shake it, because shaking can damage peptides.
6. The liquid should be clear. Do not use it if it is cloudy or has particles.
7. Write the date and the amount of water added on the vial, then refrigerate it.

Buying it

• Check the label says "Bacteriostatic" and "0.9% benzyl alcohol". Pharmacy-grade vials from makers like Hospira are the standard.
• Ameano Peptides sells a "Research Diluent Solution". Its product page only calls it a sterile aqueous solution, so check their lab report to confirm it contains benzyl alcohol. If it does not, treat it as sterile water and use a mixed vial quickly.
• Nexaph does not currently list a bacteriostatic water or diluent product.
• Buy enough for your whole protocol. You will usually need one water vial for every few peptide vials.

Possible side effects

• Stinging or burning at the injection site from the benzyl alcohol, which is common and brief
• Rare allergic reaction to benzyl alcohol