How to reconstitute peptides: step by step

Reconstitution is just adding sterile liquid to a powder vial so you can draw doses from it. The kit is short:

• The peptide vial (a lyophilized powder or cake).
• Bacteriostatic water, unless the product says otherwise. It is sterile water with benzyl alcohol as a preservative, which is what lets you puncture the vial again and again.
• A syringe to move the water. Many people use a 1 mL insulin syringe for this and draw it in two goes if needed.
• Fresh insulin syringes for the doses themselves.
• Alcohol swabs, a clean surface, and a marker for the label.

"Reconstitution solution" is a category, not one product. Bacteriostatic water, plain sterile water and saline all count. For multi-dose peptide vials, guides default to bacteriostatic water.

The water volume sets the concentration, and the concentration decides how many syringe units each dose takes.

Concentration (mg per mL) = mg of peptide in the vial divided by mL of water.

Example: a 5 mg vial plus 2 mL of water is 2.5 mg per mL, which is 2,500 mcg per mL. On a U-100 syringe, 10 units (0.10 mL) then holds 250 mcg.

How to pick a volume:

• More water makes each dose a bigger, easier-to-read number of units. Less water keeps each shot small.
• One syringe guide suggests the 0.5 mL barrel for doses of 5 to 50 units, where the lines are easy to read.
• Check that your largest planned dose fits in one syringe.

Every compound page lists the water volumes guides commonly use for each vial size, with sources. Our reconstitution calculator shows the units for your exact vial, water and dose. The full formula is in mg to units conversion.

1. Wash your hands and clear a clean, dry surface.
2. Take the peptide vial out of the fridge and let it come to room temperature, as most guides advise.
3. Check the label: the right compound, the amount in mg, and the date.
4. Look at the powder. It may be a disc, a fluffy cake or a thin film. A cracked or shrunken cake is not proof of a problem by itself, but liquid already in the vial or a broken seal is.

Flip off the plastic caps. Wipe the rubber stopper of the peptide vial and of the water vial with a fresh alcohol swab each, and let them air dry. Do not touch the rubber after swabbing.

1. Pull the syringe plunger back to the volume of water you want, filling it with air.
2. Push the needle through the stopper of the water vial and inject that air. This keeps a vacuum from forming and makes the draw smooth.
3. Turn the vial upside down and pull the plunger slowly past your line, then push back to the exact mark to clear bubbles.
4. Pull the needle out.

If you need more than the syringe holds, repeat with a fresh draw rather than guessing past the last line.

Insert the needle into the peptide vial at an angle so the tip rests against the inside wall. Push the plunger slowly and let the water run down the glass onto the powder, rather than spraying it straight at the cake.

Many powder vials are sealed under partial vacuum, so you may feel the water pull in on its own. Keep a hand on the plunger so it goes in at your pace. Community posts sometimes flag a vial with no vacuum at all as a reason to inspect it closely.

Swirl the vial or roll it slowly between your palms. Do not shake it. Guides agree that hard shaking is the most common way people damage a peptide, and foam is a sign you overdid it.

Most powders clear within a few minutes. One guide suggests letting it sit 5 to 10 minutes, and up to 30 minutes for a slow one. A few peptides dissolve poorly in water. Some guides and community members use a dilute acetic acid solution for those; that is a home workaround from guides, not something tested in studies.

1. Hold the vial to the light. It should be clear. Cloudiness, floating particles or an unexpected color are reasons not to use it. Some peptides have a natural tint, such as the blue of GHK-Cu, and the compound page says when that is normal.
2. Write the date and the water volume on the vial. You will need the volume for every dose.
3. Put it in the fridge at 2 to 8 C, away from light.

How long a mixed vial lasts: most guides say about 28 days. That number comes from the rule for punctured multi-dose vials (date them, discard within 28 days unless the maker says otherwise), not from stability tests on each peptide. See Peptide storage.

Bacteriostatic water contains 0.9% benzyl alcohol as a preservative and is sold as a multiple-dose container. Sterile water for injection has no preservative.

• Use bacteriostatic water for a vial you will draw from over days or weeks. That is the standard choice in guides.
• Sterile water is treated as single-use. One guide puts its mixed shelf life at 24 to 48 hours in the fridge.
• Tap water, bottled water or distilled water are not sterile. Never use them.

Opened bacteriostatic water: keep it in the fridge once punctured, date it, and discard it after 28 days, as many guides advise.

• Shaking the vial instead of swirling it.
• Spraying water straight onto the powder.
• Forgetting how much water went in. Without it, every dose is a guess.
• Mixing up mg and mcg in the math, which is a thousandfold error.
• Using a syringe whose scale you have not checked. See How to read an insulin syringe.
• Reusing a needle to save a syringe.