How much bacteriostatic water does each vial need?
This is the quick reference by vial size. The concentration column is the one you need to calculate any volume; the units correspond to a U-100 insulin syringe, where 100 IU equals 1 mL.
| Vial | Recommended water | Concentration | 250 mcg | 500 mcg |
|---|---|---|---|---|
| 2 mg | 1 mL | 2,000 mcg/mL | 12.5 IU | 25 IU |
| 5 mg | 1 mL | 5,000 mcg/mL | 5 IU | 10 IU |
| 10 mg | 1 mL | 10,000 mcg/mL | 2.5 IU | 5 IU |
| 15 mg | 2 mL | 7,500 mcg/mL | 3.33 IU | 6.67 IU |
| 20 mg | 2 mL | 10,000 mcg/mL | 2.5 IU | 5 IU |
| 30 mg | 2 mL | 15,000 mcg/mL | 1.67 IU | 3.33 IU |
| 50 mg | 2 mL | 25,000 mcg/mL | 1 IU | 2 IU |
| 60 mg | 3 mL | 20,000 mcg/mL | 1.25 IU | 2.5 IU |
| 100 mg | 3 mL | 33,333.33 mcg/mL | 0.75 IU | 1.5 IU |
The reference masses are volumetric calculation values for laboratory work, not an administration schedule. Material for scientific research use only.
How it is calculated, without memorizing anything
Only two operations are needed. The first gives the concentration: divide the micrograms in the vial by the milliliters of water you added. A 10 mg vial is 10,000 mcg; with 2 mL of water you get 5,000 mcg per mL.
The second gives the volume: divide the mass you need by that concentration. For 500 mcg at 5,000 mcg/mL, that is 0.1 mL. And since a U-100 insulin syringe marks 100 units per milliliter, 0.1 mL is 10 units.
That is why it is worth writing the concentration on the vial when you reconstitute it: it is the only number you need afterwards.
Why bacteriostatic water and not sterile water
Bacteriostatic water contains 0.9% benzyl alcohol, a preservative that inhibits bacterial growth after the stopper is pierced. That allows multiple draws from the same vial for about 28 days refrigerated.
Sterile water for injection contains no preservative: it is for a single draw and is then discarded. Never use tap water, non-sterile distilled water or saline, which can precipitate some peptides.
The procedure, step by step
- Let the vial and the water reach room temperature, about 15 minutes.
- Clean both stoppers with 70% isopropyl alcohol.
- Add the water slowly and against the wall of the vial, never in a direct stream onto the powder.
- Swirl the vial gently until dissolved. Do not shake it: foam indicates denaturation.
- The solution should be clear and colorless. If it comes out cloudy or with particles, discard it.
- Write down the reconstitution date and store refrigerated between 2 and 8 °C.
Frequently asked questions
Page last updated: August 19, 2026. Content reviewed regularly by the NeoPeptidos team.