How to Reconstitute Peptides: Step-by-Step Guide

Most research peptides arrive as a freeze-dried (lyophilized) powder. Before they can be used in any research protocol, they need to be reconstituted – mixed with a sterile solvent to create an injectable solution. Get this step wrong and you risk destroying the peptide, contaminating the vial, or miscalculating your dosage.

This guide walks through the entire reconstitution process, from supplies to storage, so you can handle peptides safely and accurately for research purposes.

What You Need for Peptide Reconstitution

Before you start, gather these supplies. Using the wrong materials introduces contamination risk or damages the peptide.

Bacteriostatic Water (BAC Water)

Bacteriostatic water is sterile water that contains 0.9% benzyl alcohol as a preservative. This preservative prevents bacterial growth, which means your reconstituted peptide stays usable for weeks rather than hours. You can purchase BAC water from most reputable peptide suppliers or medical supply stores.

Do not use regular tap water, distilled water (non-sterile), or saline unless your research protocol specifically calls for it. Sterile water for injection works but has no preservative – meaning you must use the entire vial within 24 hours once opened.

Insulin Syringes

Use 1 mL (100 unit) insulin syringes with attached needles for drawing and injecting. For reconstitution, you can also use a larger 3 mL syringe with a separate 18-21 gauge needle to draw the BAC water more easily. The insulin syringe markings make dosage measurement straightforward.

Alcohol Swabs

Standard 70% isopropyl alcohol prep pads. You will use these to sterilize the rubber stoppers on both the BAC water vial and the peptide vial before inserting a needle.

Optional but Recommended

• Mixing needle (18-21 gauge): Wider gauge makes drawing BAC water faster
• Sharps container: For safe needle disposal
• Clean workspace: A wiped-down surface free from dust and debris

Step-by-Step Reconstitution Process

Follow these steps carefully. Rushing through reconstitution is the number one cause of peptide degradation during handling.

Step 1: Prepare Your Workspace

Wash your hands thoroughly. Wipe down your work surface with isopropyl alcohol. Lay out all supplies so everything is within reach. You want to minimize the time vials are open or exposed.

Step 2: Check the Peptide Vial

Inspect the lyophilized powder. It should appear as a white or off-white cake or powder at the bottom of the vial. If the powder looks discolored (yellow, brown) or the vial seal is broken, do not use it. Always verify the label matches the peptide you ordered and check the expiration date.

Step 3: Swab the Vial Stoppers

Use alcohol swabs to clean the rubber stopper on both the BAC water vial and the peptide vial. Let the alcohol evaporate for about 10 seconds before inserting a needle. This step prevents bacteria from entering either vial.

Step 4: Draw the Bacteriostatic Water

Using a clean syringe, draw your desired amount of BAC water. The amount you add determines the concentration of your solution – more on dosage calculations below. Common amounts are 1 mL or 2 mL per vial, depending on the peptide quantity and desired concentration.

Insert the needle into the BAC water vial (inverted) and slowly draw to your target volume. Remove air bubbles by tapping the syringe and pushing them out gently.

Step 5: Add Water to the Peptide Vial

This is the most important step. Insert the needle into the peptide vial through the rubber stopper. Aim the needle at the inside wall of the vial, not directly at the powder. Slowly depress the plunger and let the water trickle down the glass wall.

Do NOT inject the water directly onto the powder. Do NOT shake, swirl aggressively, or otherwise agitate the vial. Peptides are fragile molecules – rough handling breaks peptide bonds and degrades the compound.

Step 6: Let It Dissolve

After adding the water, gently tilt the vial back and forth or roll it between your palms. Most peptides dissolve within 1-3 minutes. Some may take up to 10 minutes. If small particles remain after 10 minutes, place the vial in the refrigerator for 30 minutes and check again. Do not shake.

The resulting solution should be clear or very slightly hazy. If it is cloudy, contains visible particles that will not dissolve, or appears discolored, the peptide may be degraded.

Step 7: Label and Store

Write the peptide name, reconstitution date, concentration, and volume on a small label and attach it to the vial. Store immediately in the refrigerator at 2-8 degrees Celsius (36-46 degrees Fahrenheit).

Dosage Calculations

Getting the math right is essential. Here is the straightforward formula:

Concentration = Total peptide (mcg) / Volume of BAC water added (mL)

Example 1: BPC-157 (5 mg vial)

You have a 5 mg (5,000 mcg) vial of BPC-157 and add 2 mL of BAC water.

• Concentration: 5,000 mcg / 2 mL = 2,500 mcg per mL
• Each 0.1 mL (10 units on an insulin syringe) = 250 mcg
• For a 250 mcg dose, draw to the 10-unit mark

Example 2: TB-500 (5 mg vial)

You have a 5 mg (5,000 mcg) vial of TB-500 and add 1 mL of BAC water.

• Concentration: 5,000 mcg / 1 mL = 5,000 mcg per mL
• Each 0.1 mL (10 units) = 500 mcg
• For a 2,000 mcg (2 mg) dose, draw to the 40-unit mark

General Dosage Table

Tip: Choose a BAC water volume that gives you round dosage numbers. This reduces the chance of measurement errors when drawing with an insulin syringe.

Common Mistakes to Avoid

1. Injecting Water Directly Onto the Powder

This is the single most common error. Blasting water onto lyophilized powder can denature the peptide through mechanical force. Always aim at the vial wall and let water trickle down gently.

2. Shaking the Vial

Peptides are proteins (or protein fragments). Aggressive shaking creates foam and can break peptide bonds through a process called mechanical denaturation. Gentle rolling or tilting only.

3. Using Non-Sterile Water

Regular distilled water from the store is not sterile. It can introduce bacteria that will multiply in your reconstituted vial, especially without a preservative. Always use bacteriostatic water or sterile water for injection.

4. Forgetting to Swab Vial Tops

Rubber stoppers are not sterile out of the package. Even handling them briefly can transfer skin bacteria. Always swab with alcohol before needle insertion.

5. Reusing Needles

Each time you draw from the vial, use a fresh needle. Reused needles are dull (increasing rubber core risk) and contaminated. Insulin syringes are inexpensive – do not cut corners here.

6. Incorrect Math

Double-check your calculations before drawing any dose. A miscalculation by a factor of 10 is surprisingly easy – 5 mg versus 5,000 mcg can confuse researchers who are not used to unit conversions. Remember: 1 mg = 1,000 mcg.

7. Leaving Reconstituted Peptides at Room Temperature

Once reconstituted, peptides degrade rapidly at room temperature. Refrigerate immediately after each use. Never leave a reconstituted vial on your desk for hours.

Storage After Reconstitution

Proper storage is what separates a vial that lasts 4 weeks from one that is useless after 3 days.

Refrigeration (2-8 C / 36-46 F)

Store all reconstituted peptides in the refrigerator. Most reconstituted peptides remain stable for 3-4 weeks when stored properly in bacteriostatic water. Some more stable peptides like BPC-157 may last up to 6 weeks, while more fragile ones like certain growth hormone releasing peptides may show degradation after 2 weeks.

Freezing

For unreconstituted (lyophilized) peptides, freezer storage at -20 C extends shelf life to 12-24 months or longer. However, do not freeze reconstituted peptides unless you are certain the peptide tolerates freeze-thaw cycles. Most do not. Freezing reconstituted solution creates ice crystals that can damage peptide structures.

Light Protection

Some peptides are light-sensitive. Store vials in a dark area of the refrigerator or wrap them in aluminum foil. This is especially important for peptides like Melanotan II and PT-141.

Handling Practices

• Minimize the number of times you puncture the rubber stopper – each puncture is a contamination risk
• Always swab the stopper before each draw
• Return the vial to the refrigerator immediately after drawing your dose
• If the solution turns cloudy or develops visible particles, discard it
• Write the reconstitution date on every vial so you know when to discard

Quick Reference Checklist

1. Wash hands, clean workspace
2. Inspect peptide vial for damage or discoloration
3. Swab both vial stoppers with alcohol
4. Draw measured BAC water into syringe
5. Inject water slowly down the inside wall of the peptide vial
6. Gently tilt or roll to dissolve – never shake
7. Verify solution is clear
8. Label the vial with name, date, and concentration
9. Refrigerate immediately

Where to Buy Quality Peptides and Supplies

The reconstitution process only matters if you are starting with a quality product. Low-purity peptides may not dissolve properly or may contain contaminants that affect research results. Check our best peptide companies guide for suppliers that provide third-party tested, high-purity research peptides along with bacteriostatic water and supplies.

For a deeper look at verifying what you are buying, read our guide on how to verify peptide quality through COA analysis.