How to Reconstitute Peptides (Step by Step)
Most peptides arrive as a freeze-dried (lyophilized) powder. Before you can measure a dose, you need to mix the vial with bacteriostatic water — and get the math right so every draw is consistent.
What you need
- Your peptide vial (the label shows the total amount, e.g. 5 mg or 10 mg)
- Bacteriostatic water (BAC water) — sterile water with 0.9% benzyl alcohol
- A mixing syringe (3 mL is convenient) and insulin syringes for dosing
- Alcohol swabs
Step 1: Decide how much BAC water to add
There's no single correct volume — it's a trade-off between precision and injection volume. Common choices:
- 5 mg vial + 2 mL water → 2.5 mg/mL (2,500 mcg/mL)
- 10 mg vial + 2 mL water → 5 mg/mL (5,000 mcg/mL)
- 10 mg vial + 1 mL water → 10 mg/mL — very concentrated, small injection volumes but less forgiving measuring
A good rule of thumb: pick a volume that makes your typical dose land between 5 and 30 units on a 1 mL (100-unit) insulin syringe. Big enough to measure accurately, small enough to inject comfortably.
Step 2: Mix gently
- Swab both vial tops with alcohol.
- Draw your chosen volume of BAC water.
- Inject the water slowly, aiming the stream at the inside wall of the vial — not directly onto the powder.
- Let it dissolve on its own, or swirl gently. Don't shake — vigorous shaking can damage fragile peptide chains.
- The solution should turn clear. Cloudiness or particles are a red flag.
Step 3: Calculate your dose in syringe units
The formula is simple:
units to draw = (dose in mcg ÷ concentration in mcg/mL) × 100
Example: a 5 mg vial mixed with 2 mL is 2,500 mcg/mL. For a 250 mcg dose: (250 ÷ 2,500) × 100 = 10 units on a standard insulin syringe.
LogMyPeptides does this math for you — enter your vial size and water volume once, and every log entry shows the exact units to draw. There's also a built-in unit converter for mg, mcg and IU.
Step 4: Store it properly
- Keep reconstituted vials refrigerated (2–8 °C), never frozen.
- Store upright and away from light.
- Most reconstituted peptides are used within 3–6 weeks; when in doubt, follow the supplier's guidance.
- Unmixed lyophilized vials keep much longer — fridge or freezer.
Common mistakes to avoid
- Shaking the vial instead of swirling gently
- Forgetting which volume of water you added — write it on the vial
- Reusing a vial past its stable window
- Eyeballing doses instead of calculating units from the actual concentration
Tracking each vial's size, water volume and concentration in your log means you never have to redo the math — and your dose history stays accurate across vials. See the peptide library for typical dosing ranges per compound.