Reconstitution is the process of dissolving a lyophilized (freeze-dried) peptide powder in a liquid solvent to create a solution suitable for injection. Done correctly, it produces a stable, accurately dosed solution. Done incorrectly, it can degrade the peptide, introduce contamination, or result in inaccurate dosing. This guide covers the complete process from equipment to calculation.

What You Need

Bacteriostatic water (BAC water): Sterile water containing 0.9% benzyl alcohol as a preservative. The benzyl alcohol inhibits microbial growth, extending the usable life of your reconstituted solution to approximately 28 days when refrigerated. Do not use plain sterile water - it has no preservative and is unsuitable for multi-dose vials.
Insulin syringes: U-100 insulin syringes (100 units = 1 mL) are standard. U-100 markings make dosing calculations straightforward. 28-31 gauge needles minimize injection site trauma.
Alcohol swabs: 70% isopropyl alcohol swabs. Use to sterilize vial tops before every puncture - both the peptide vial and the BAC water vial.
The peptide vial: Typically 2 mg, 5 mg, or 10 mg lyophilized powder in a sealed glass vial.

Why Bacteriostatic Water, Not Sterile Water

This is the most commonly misunderstood aspect of reconstitution. Sterile water is single-use - once the vial is punctured, it is no longer sterile and microbial growth can occur rapidly. BAC water's 0.9% benzyl alcohol preservative prevents microbial contamination for the life of the solution, enabling safe multi-dose use over several weeks. For any multi-dose peptide vial, BAC water is required, not optional.

Step-by-Step Reconstitution

Step 1: Prepare Your Workspace

Work on a clean, flat surface. Wash hands thoroughly or use nitrile gloves. Gather all materials before starting. Ensure adequate lighting.

Step 2: Calculate Your Reconstitution Volume

Before drawing any liquid, determine how much BAC water you will add. This determines your final concentration. The standard approach:

Adding 1 mL BAC water to a 5 mg vial = 5 mg/mL (5,000 mcg/mL)
Adding 2 mL BAC water to a 5 mg vial = 2.5 mg/mL (2,500 mcg/mL)
Adding 2 mL BAC water to a 2 mg vial = 1 mg/mL (1,000 mcg/mL)

Lower concentration (more BAC water) = easier to measure small doses accurately on an insulin syringe. Higher concentration = smaller injection volume per dose.

Step 3: Swab the Vial Tops

Wipe the rubber stopper of both the BAC water vial and the peptide vial with a fresh alcohol swab. Allow to air dry for 10-15 seconds before puncturing - residual alcohol on the stopper can enter the vial and affect the peptide.

Step 4: Draw the BAC Water

Insert the insulin syringe into the BAC water vial. Draw your calculated volume slowly. Pull back the plunger slightly beyond your target volume, then gently push back to the exact mark to eliminate air bubbles.

Step 5: Add BAC Water to the Peptide Vial

This step requires care. Do not inject the BAC water directly onto the lyophilized powder cake - this can cause foaming and degradation. Instead:

Insert the needle through the rubber stopper at an angle, directing the needle tip toward the glass wall of the vial
Let the BAC water run slowly down the side of the vial
Do not spray directly onto the powder
If adding multiple mL, you can inject in portions - insert, release some liquid, remove partially, repeat

Step 6: Dissolve the Peptide

Do not shake the vial. Agitation from shaking creates mechanical stress that can degrade peptide structure (particularly for larger peptides). Instead:

Gently swirl the vial in slow circles
Optionally, roll the vial between your palms
Allow to sit at room temperature for 5-10 minutes if needed
The solution should become clear. Some peptides produce a slightly cloudy or tinted solution - check the supplier documentation for what is expected for your specific compound

Dosing Calculations: Real Examples

Example 1: BPC-157, 5 mg vial, 2 mL BAC water

Calculation	Value
Peptide amount	5 mg = 5,000 mcg
BAC water added	2 mL = 2,000 mcL
Concentration	5,000 mcg / 2,000 mcL = 2.5 mcg/mcL
Target dose	250 mcg
Volume to inject	250 / 2.5 = 100 mcL = 10 units on U-100 syringe

Example 2: Ipamorelin, 2 mg vial, 2 mL BAC water

Calculation	Value
Peptide amount	2 mg = 2,000 mcg
BAC water added	2 mL = 2,000 mcL
Concentration	1 mcg/mcL
Target dose	200 mcg
Volume to inject	200 / 1 = 200 mcL = 20 units on U-100 syringe

Quick Reference: U-100 Syringe Markings

On a U-100 insulin syringe: 1 unit = 0.01 mL = 10 mcL. So:

10 units = 0.1 mL = 100 mcL
20 units = 0.2 mL = 200 mcL
50 units = 0.5 mL = 500 mcL

Storage

Unreconstituted lyophilized peptide: Room temperature for transport (days); refrigerate (2-8C) for weeks; freeze (-20C) for months to years. Keep away from light.
Reconstituted solution: Refrigerate (2-8C) immediately. Use within 28 days. Do not freeze reconstituted peptides - ice crystal formation damages peptide structure.
Label your vials: Date of reconstitution + compound + concentration. This is not optional if you have multiple vials.

Common Mistakes to Avoid

Shaking instead of swirling: Mechanical agitation degrades peptides. Always swirl gently.
Injecting BAC water directly onto the powder: Causes foaming and potential denaturation. Aim for the glass wall.
Not swabbing vial tops: Every puncture is an opportunity for contamination. Swab every time.
Using plain sterile water for multi-dose vials: No preservative = contamination risk. Always BAC water for multi-dose use.
Freezing reconstituted solution: Damages peptide structure. Only freeze lyophilized (unreconstituted) powder.
Miscalculating concentration: Double-check your math before the first dose. A 10x concentration error means 10x the dose.
Not dating vials: A reconstituted peptide 6 weeks past reconstitution is not reliable. Date everything.

Subcutaneous Injection Technique

Once reconstituted and dosed accurately in the syringe:

Common SubQ injection sites: lower abdomen (2-3 inches from navel), outer thigh, upper buttock
Rotate injection sites to avoid lipohypertrophy (fat accumulation from repeated injection in one area)
Pinch skin, insert needle at 45-degree angle for thinner individuals or 90 degrees with more subcutaneous fat
Inject slowly and steadily; withdraw needle smoothly
Mild swelling or redness at the injection site is normal and typically resolves within hours

How to Reconstitute Peptides: Step-by-Step Guide