How to Reconstitute Peptides
Peptides arrive as lyophilized, or freeze-dried, powder. They are shipped that way because the dry form is far more stable. Before use, the powder is reconstituted with bacteriostatic water. Here is how to do it correctly: mixing, the dosing math, and storage.
What you need
- The lyophilized peptide vial
- Bacteriostatic water (sterile water with benzyl alcohol, pharmaceutical grade)
- A U-100 insulin syringe
- Alcohol swabs
Step by step
- Swab the rubber stopper on both the peptide vial and the bac water vial.
- Draw your chosen amount of bacteriostatic water into the syringe. The amount you choose sets the concentration (see the math below).
- Inject the water slowly down the inside wall of the peptide vial. Never spray it directly onto the powder.
- Swirl gently. Do not shake. Shaking can damage the peptide. Wait until the solution is fully dissolved and clear.
- Refrigerate. The vial is now ready to measure from.
The dosing math
This is the part people overthink. Three lines:
- Concentration (mg/mL) = peptide mg divided by water mL
- Dose volume (mL) = desired dose mg divided by concentration
- Syringe units (U-100) = dose volume mL times 100
Worked example with a 10 mg vial:
| Bac water added | Concentration | 0.25 mg dose | 0.5 mg dose |
|---|---|---|---|
| 1 mL | 10 mg/mL | 2.5 units | 5 units |
| 2 mL | 5 mg/mL | 5 units | 10 units |
Tip: adding more water lowers the concentration, which spreads a small dose across more syringe units and makes it easier to measure accurately.
Storage
Store reconstituted vials in the refrigerator at 2 to 8 degrees Celsius and keep them out of light. Use within the window noted on your COA, often a few weeks. Do not freeze a reconstituted vial; freeze-thaw cycles degrade the peptide. Unopened lyophilized powder is far more stable and can be kept longer and colder.
Mistakes to avoid
- Spraying water straight onto the powder instead of down the wall
- Shaking the vial hard
- Leaving a reconstituted vial at room temperature
- Using plain sterile water for a multi-use vial instead of bacteriostatic water
Bac water ships with your order
Pharmaceutical-grade bacteriostatic water, ready to reconstitute.
Browse the catalogFAQ
How much bacteriostatic water should I use?
Any amount works; more water means a lower concentration, which makes small doses easier to measure. One to two milliliters per vial is common.
Can I use regular water?
No. Use bacteriostatic water, which is sterile water with benzyl alcohol, so a multi-use vial stays preserved between uses.
How long does a reconstituted vial last?
Refrigerated, typically several weeks. Follow the window on your COA and discard if it turns cloudy.
Related: How to Read a Peptide COA
Try the peptide reconstitution calculator to get your exact draw volume.