How to Reconstitute Peptides

A complete step-by-step guide to dissolving lyophilized peptide powder in bacteriostatic water — including concentration math, worked examples, and troubleshooting.

Why Reconstitution Is Necessary

Research peptides are supplied as lyophilized (freeze-dried) powder because peptides are significantly more stable in dry form than in solution. A lyophilized vial stored at −20°C can last 1–2 years; the same peptide reconstituted and stored at refrigerator temperature should be used within 14–30 days. Reconstitution — dissolving the powder in a liquid diluent — is required before a peptide can be administered by injection.

What You Need

• Peptide vial (lyophilized powder, sealed with rubber stopper)
• Bacteriostatic water (BAC water) — sterile water with 0.9% benzyl alcohol preservative
• Insulin syringe(s) — U-100, typically 1 mL capacity with attached needle
• Alcohol swabs — for sterilizing vial stoppers before each puncture
• Sharps container — for safe needle disposal
• Refrigerator — for storing reconstituted vials at 2–8°C

The Reconstitution Process

1. Prepare your workspace. Work on a clean, flat surface. Wash hands thoroughly. Lay out your supplies.
2. Allow vials to reach room temperature. Remove both the peptide vial and BAC water vial from refrigerator/freezer and let them sit at room temperature for 5–10 minutes. This prevents condensation from entering when the stopper is punctured.
3. Swab the stoppers. Wipe the rubber stopper of both vials with an alcohol swab. Allow to air dry for 30–60 seconds before puncturing.
4. Draw BAC water. Insert the insulin syringe needle through the center of the BAC water vial stopper. Draw the desired volume of BAC water. Remove the needle cleanly.
5. Inject into the peptide vial — slowly, along the wall. Insert the needle through the center of the peptide vial stopper. Angle the needle so the BAC water stream runs down the inside glass wall of the vial, NOT directly onto the powder. Inject slowly. Direct stream onto the powder can cause foaming, which may degrade the peptide.
6. Dissolve gently. After injecting, gently swirl or roll the vial between your fingers. Do NOT shake. Most peptides dissolve within 1–2 minutes. Some (like longer-chain peptides) may take up to 10 minutes. The solution should be clear and colorless when complete.
7. Label and refrigerate. Write the reconstitution date on the vial label. Refrigerate immediately at 2–8°C. Do not freeze reconstituted peptide solutions — freeze-thaw cycles degrade potency.

Concentration Math

Concentration (mg/mL) = Total peptide amount (mg) ÷ BAC water volume (mL)

How Much BAC Water to Add?

More BAC water = lower concentration = larger injection volume per dose. Less BAC water = higher concentration = smaller injection volume per dose. The "right" amount depends on your desired dose and your target injection volume. General guidelines:

• Aim for injection volumes that require at least 5–10 syringe units — easier to measure accurately.
• Avoid injection volumes above 1.0 mL (100 units) — split into two sites if needed.
• Use the PeptidEdge Calculator to find your exact injection volume for any BAC water amount.

Troubleshooting

• Powder won't dissolve: Some peptides take 5–10 minutes. Continue gentle swirling. If still cloudy after 10 minutes, allow to sit in refrigerator for 1 hour and try again. Do not heat.
• Solution looks cloudy/has particles: Possible contamination or peptide aggregation. Do not use. Discard and use a fresh vial.
• Foam in vial: Caused by injecting too fast or shaking. Allow foam to settle before drawing doses. Next time, inject more slowly along the vial wall.
• Vial has negative pressure (hard to inject): Normal for sealed vials. Slightly withdraw plunger after inserting needle to equalize pressure before injecting.

Reconstituted Storage Rules