Guide
Peptide Reconstitution Guide
How to properly reconstitute lyophilized peptides with bacteriostatic water. Step-by-step instructions, dosing calculations, and storage.
What Is Reconstitution?
Reconstitution is the process of adding a liquid solvent to a lyophilized (freeze-dried) peptide powder to create an injectable solution. Most research peptides are supplied as a dry powder in a sealed vial. They must be mixed with a sterile solvent before use.
This process is straightforward but must be done carefully to preserve the peptide's integrity. Improper handling — such as shaking the vial, using the wrong solvent, or contaminating the solution — can degrade or destroy the peptide.
What You Need
Before reconstituting, gather the following:
— Lyophilized peptide vial (sealed, stored per manufacturer instructions) — Bacteriostatic water (BAC water) — sterile water with 0.9% benzyl alcohol as a preservative — Insulin syringes (typically 1 mL / 100 unit syringes) — Alcohol swabs for sterilizing vial tops — Clean workspace
Why Bacteriostatic Water?
Bacteriostatic water contains 0.9% benzyl alcohol, which inhibits bacterial growth. This allows the reconstituted peptide to be stored and used over multiple days (typically up to 30 days refrigerated). Sterile water for injection can also be used but contains no preservative — use within 24 hours if using sterile water.
Do NOT use normal tap water, distilled water, or saline unless specifically instructed. These can degrade the peptide or cause injection site reactions.
Step-by-Step Reconstitution
1. Wash your hands thoroughly.
2. Wipe the top of the peptide vial and the BAC water vial with an alcohol swab. Allow to dry.
3. Draw your desired amount of BAC water into the syringe. Common amounts: 1 mL or 2 mL (see dosing calculations below).
4. Insert the needle into the peptide vial at an angle, with the tip touching the inner glass wall — NOT aimed directly at the powder.
5. Slowly depress the plunger, allowing the water to trickle down the side of the vial onto the powder. Do NOT squirt water directly onto the peptide cake.
6. Once all water is added, remove the syringe gently.
7. DO NOT SHAKE the vial. Instead, gently swirl it or roll it between your palms. Most peptides dissolve within 1–3 minutes. Some may take up to 10 minutes.
8. Once fully dissolved (solution should be clear, not cloudy), the peptide is ready for use.
9. Store the reconstituted vial in the refrigerator (2–8°C). Do not freeze reconstituted peptides.
Dosing Calculations
After reconstitution, you need to know how much solution to draw for your desired dose. The formula is simple:
Concentration = Total peptide (mcg) ÷ Total solvent (mL)
Example: 5 mg (5,000 mcg) peptide reconstituted with 2 mL BAC water: 5,000 mcg ÷ 2 mL = 2,500 mcg per mL
Using a 1 mL (100 unit) insulin syringe: Each "unit" mark = 0.01 mL = 25 mcg
So for a 250 mcg dose: draw to the 10 unit mark. For a 500 mcg dose: draw to the 20 unit mark.
Common Reconstitution Amounts
5 mg vial + 1 mL BAC water = 5,000 mcg/mL (50 mcg per unit mark) 5 mg vial + 2 mL BAC water = 2,500 mcg/mL (25 mcg per unit mark) 10 mg vial + 2 mL BAC water = 5,000 mcg/mL (50 mcg per unit mark) 10 mg vial + 3 mL BAC water = 3,333 mcg/mL (33.3 mcg per unit mark)
Using 2 mL is the most common choice — it provides easy math and enough volume for practical syringe measurements.
Storage After Reconstitution
Reconstituted peptides should be stored in the refrigerator at 2–8°C (36–46°F). Most peptides remain stable for 21–30 days when reconstituted with bacteriostatic water.
Do NOT freeze reconstituted peptides — ice crystal formation can damage the peptide structure.
Keep vials upright and away from light. Do not leave at room temperature for extended periods.
If the solution becomes cloudy, discolored, or contains visible particles, discard it.
Common Mistakes to Avoid
— Shaking the vial (denatures the peptide — always swirl gently) — Squirting water directly onto the powder (can damage the peptide cake) — Using too little solvent (makes accurate dosing difficult) — Forgetting to refrigerate after mixing — Double-dipping syringes (use a fresh syringe each time you draw) — Reconstituting too far in advance (mix when you're ready to start using) — Leaving the vial at room temperature for hours