How to Reconstitute Peptides
The complete guide to mixing lyophilized peptides with bacteriostatic water — from supplies to your first dose draw.
1 What Is Reconstitution?
Reconstitution is the process of dissolving freeze-dried (lyophilized) peptide powder into a liquid solution using bacteriostatic water. This converts the stable powder into an injectable research solution.
Peptides are shipped as dry powder because it is far more stable than liquid form — lyophilized peptides can maintain potency for 12-24 months at refrigerator temperatures, while reconstituted solutions typically last 25-30 days.
2 Supplies You Will Need
3 Choosing Your Diluent
The diluent (liquid) you use to reconstitute affects how long the solution remains viable.
| Diluent | Preservative | Multi-Use? | Solution Lifespan | Best For |
|---|---|---|---|---|
| Bacteriostatic Water (BAC) | 0.9% benzyl alcohol | Yes | 25-30 days | Standard choice for all peptides |
| Sterile Water | None | No | 24-48 hours | Single-use situations only |
| Normal Saline (0.9%) | None | No | 24-48 hours | When BAC water is unavailable |
Never use tap water, distilled drinking water, or any non-sterile liquid. These will contaminate your peptide and potentially introduce harmful bacteria.
4 How Much BAC Water to Add
The volume of BAC water you add determines the concentration of your solution — and therefore how much liquid you draw for each dose.
The formula is simple:
Common Reconstitution Volumes
| Peptide | BAC Water | Concentration | 250mcg = ? units |
|---|---|---|---|
| 5mg | 1mL | 5mg/mL (5,000mcg/mL) | 5 units |
| 5mg | 2mL | 2.5mg/mL (2,500mcg/mL) | 10 units |
| 10mg | 2mL | 5mg/mL (5,000mcg/mL) | 5 units |
| 10mg | 3mL | 3.33mg/mL (3,333mcg/mL) | 7.5 units |
Less BAC water = more concentrated solution = smaller injection volumes (but harder to measure small doses precisely). More BAC water = diluted solution = larger volumes (easier to measure but uses more syringe capacity).
Use our Reconstitution Calculator to find the optimal volume for your vial size and dosing protocol.
5 Step-by-Step Reconstitution
Prepare Your Workspace
Clean a flat surface. Gather all supplies. Wash hands thoroughly or use gloves. Have your sharps container within reach.
Sterilize Both Vial Tops
Wipe the rubber stopper of both the peptide vial and BAC water vial with separate alcohol prep pads. Let them air dry for a few seconds.
Draw BAC Water
Using a fresh insulin syringe, draw air equal to your desired BAC water volume. Insert the needle into the BAC water vial, inject the air, then draw the water. This air exchange prevents a vacuum from forming.
Add Water to Peptide Vial
Insert the needle through the peptide vial stopper. Slowly release the BAC water, aiming it against the inside glass wall — not directly onto the powder. Let the water trickle down gently.
Let It Dissolve
Set the vial on a flat surface and wait. Most peptides dissolve within 2-5 minutes. You can gently roll the vial between your fingers to assist — never shake or swirl aggressively, as this can damage peptide bonds.
Verify Clarity
The solution should be completely clear and colorless. If you see particles, cloudiness, or discoloration, do not use it. Some stubborn powders may need additional time — refrigerate and check again in 30 minutes.
Refrigerate Immediately
Store the reconstituted vial upright in the refrigerator (2-8°C). Label it with the date, peptide name, and concentration. The clock starts now — use within 25-30 days.
6 Drawing a Dose
Once reconstituted, drawing a dose follows a similar sterile technique:
- Calculate your dose volume using the concentration you created (or use our calculator)
- Swab the vial stopper with a fresh alcohol pad
- Draw air into a fresh syringe equal to the dose volume
- Insert the needle through the stopper and inject the air
- Invert the vial and draw the liquid to your target mark
- Remove the needle and tap out any air bubbles
- Verify the measurement at the top edge of the rubber plunger
7 Worked Examples
Example 1: BPC-157 (5mg vial, 250mcg dose)
250mcg ÷ 2,500mcg/mL = 0.10mL = 10 units on syringe
Doses per vial: 5,000mcg ÷ 250mcg = 20 doses
Example 2: Semaglutide (5mg vial, 0.25mg starting dose)
0.25mg ÷ 2mg/mL = 0.125mL = 12.5 units on syringe
Doses per vial: 5mg ÷ 0.25mg = 20 doses
Example 3: CJC-1295/Ipamorelin (10mg vial, 300mcg dose)
300mcg ÷ 5,000mcg/mL = 0.06mL = 6 units on syringe
Doses per vial: 10,000mcg ÷ 300mcg = 33 doses
8 Common Mistakes to Avoid
Shaking the Vial
Vigorous shaking can break peptide bonds through mechanical stress. Gentle rolling between fingers is fine. If undissolved powder remains, refrigerate and wait — do not shake.
Spraying Water Directly on Powder
Forcing BAC water directly onto the lyophilized cake can damage the peptide. Always aim the stream at the glass wall and let water trickle down to the powder.
Using Too Little BAC Water
Extremely concentrated solutions (e.g., 0.5mL in a 10mg vial) can be difficult to dose accurately. Consider whether a more dilute solution would make measurements easier.
Reusing Syringes
Used needles carry bacteria and become dull after a single use. Always use a fresh syringe for each dose draw and each reconstitution.
Skipping Sterilization
Even "clean-looking" vial stoppers can harbor bacteria. Always swab with alcohol before inserting a needle — every single time.
Reconstituting at Room Temperature
Let refrigerated peptides warm to room temperature for 5-10 minutes before reconstituting. Adding cold BAC water to a cold vial is fine, but extreme temperature differences should be avoided.
9 Troubleshooting
| Problem | Likely Cause | Solution |
|---|---|---|
| Powder won't dissolve | Normal for some peptides | Refrigerate upright for 30-60 min. Gently roll periodically. Never shake. |
| Solution is cloudy | Possible contamination or degradation | If it doesn't clear within 1 hour, discard and use a new vial. |
| Yellow or colored solution | Peptide oxidation / degradation | Discard. Do not use discolored solutions. |
| Excessive foam | BAC water added too forcefully | Let foam settle naturally. The peptide is likely fine underneath. |
| Stopper crumbling | Repeated needle punctures in same spot | Rotate insertion points. If rubber particles are visible in solution, discard. |
10 Post-Reconstitution Storage
For complete storage protocols, see our Peptide Storage Guide.