How to Reconstitute Peptides: A Step-by-Step Guide
Learn the proper technique for reconstituting lyophilized peptides with bacteriostatic water, including dosage calculations and common mistakes to avoid.
Looking for the quick version? The interactive Peptide Usage Guide covers reconstitution alongside every other administration route (oral, nasal, sublingual, topical), and links straight to the Dosing Calculator for the exact numbers.
What Is Reconstitution?
Reconstitution is the process of adding a solvent — typically bacteriostatic water (BAC water) — to a lyophilized (freeze-dried) peptide to create an injectable solution. It's one of the most important steps in peptide research, and doing it correctly ensures accurate dosing and peptide stability.
What You'll Need
- Lyophilized peptide vial (sealed, stored properly)
- Bacteriostatic water (BAC water with 0.9% benzyl alcohol)
- Insulin syringes (1mL, 29–31 gauge)
- Alcohol swabs for sterilization
- A clean, flat workspace
Do not use sterile water or saline unless your protocol specifically calls for it. BAC water contains a preservative that prevents bacterial growth, giving your reconstituted peptide a longer usable life.
Step-by-Step Reconstitution
Step 1: Determine Your Volume
Before you add water, decide how much BAC water to use. This determines your concentration and makes dosing math easier.
A common approach: add 1mL of BAC water per 5mg of peptide. This gives you a clean concentration to work with.
| Peptide Amount | BAC Water | Concentration | |----------------|-----------|---------------| | 5mg | 1mL | 5mg/mL (5000mcg/mL) | | 10mg | 2mL | 5mg/mL (5000mcg/mL) | | 5mg | 2mL | 2.5mg/mL (2500mcg/mL) |
Step 2: Sterilize
Wipe the rubber stopper on both the peptide vial and the BAC water vial with an alcohol swab. Let them air dry for a few seconds.
Step 3: Draw the BAC Water
Using a fresh insulin syringe, draw your calculated volume of BAC water. Pull back the plunger slowly to avoid air bubbles.
Step 4: Add Water to the Peptide Vial
This is the critical step. Insert the needle through the rubber stopper and aim the stream at the glass wall of the vial — not directly onto the lyophilized powder.
Let the water trickle down the side of the vial gently. This prevents damaging the peptide structure with direct force.
Step 5: Let It Dissolve
Do not shake the vial. Most peptides will dissolve within 1–3 minutes on their own. If the powder hasn't fully dissolved, gently roll the vial between your palms or swirl it in a slow circular motion.
Some peptides (particularly larger ones like CJC-1295) may take a few extra minutes. Be patient.
Step 6: Label and Store
Label the vial with:
- Peptide name
- Concentration (e.g., 5000mcg/mL)
- Date of reconstitution
Refrigerate immediately at 2–8°C. Use within 4–6 weeks.
Calculating Your Dose
Once reconstituted, you need to convert your desired dose (in mcg) to a volume (in mL or units on your syringe).
Formula: Dose (mL) = Desired dose (mcg) ÷ Concentration (mcg/mL)
Example: BPC-157
- Vial: 5mg peptide reconstituted with 1mL BAC water
- Concentration: 5000mcg/mL
- Desired dose: 250mcg
- Volume: 250 ÷ 5000 = 0.05mL = 5 units on an insulin syringe
Example: Ipamorelin
- Vial: 5mg peptide reconstituted with 2mL BAC water
- Concentration: 2500mcg/mL
- Desired dose: 200mcg
- Volume: 200 ÷ 2500 = 0.08mL = 8 units on an insulin syringe
Common Mistakes
Spraying water directly onto the powder
This can denature the peptide. Always aim at the vial wall.
Shaking the vial
Shaking creates foam and can damage the peptide chain. Swirl gently or let it dissolve on its own.
Using sterile water instead of BAC water
Sterile water has no preservative. Peptides reconstituted with sterile water must be used within 24–48 hours or frozen in single-use aliquots.
Not labeling the vial
Once reconstituted, all vials look the same — a clear liquid. Always label immediately.
Storing at room temperature
Reconstituted peptides degrade rapidly at room temperature. Refrigerate as soon as the peptide is dissolved.
Multi-Vial Protocols
If your protocol involves multiple peptides (e.g., CJC-1295 + Ipamorelin), reconstitute each peptide in its own vial. You can draw from both vials into a single syringe for combined injection, but do not mix the lyophilized powders.
Draw the first peptide, then without removing the needle from the syringe, pierce the second vial and draw the second peptide. Inject the combined dose as a single subcutaneous injection.
When to Discard
Discard a reconstituted peptide if:
- It's been more than 6 weeks since reconstitution
- The solution appears cloudy, discolored, or contains particles
- The vial has been left unrefrigerated for more than 4 hours
- You suspect contamination (e.g., the stopper was touched or the vial was unsealed)
When in doubt, use a fresh vial. The cost of a replacement is always less than the cost of compromised research.