How to reconstitute a peptide, step by step
Reconstitution is dissolving a freeze-dried (lyophilised) peptide in bacteriostatic water so it can be drawn into a syringe. The calculator does the arithmetic; the method below is the physical process it assumes.
- Sanitise. Wipe both the peptide vial stopper and the BAC-water vial with an alcohol swab and let them dry.
- Add the water slowly. Draw your chosen volume of bacteriostatic water and let it run down the inside wall of the vial — never inject it straight onto the powder.
- Swirl, don’t shake. Gently roll the vial until the powder fully dissolves. Shaking can damage fragile peptides.
- Let it settle, then read the units to draw from the calculator and store the vial per your label’s beyond-use date.
Worked example: a 10 mg vial at a 250 mcg dose
Say your provider prescribed 250 mcg and you have a 10 mg vial you plan to reconstitute with 2 mL of BAC water:
- Concentration — 10 mg ÷ 2 mL = 5 mg/mL (5000 mcg/mL).
- Volume for your dose — 250 mcg ÷ 5000 mcg/mL = 0.05 mL.
- Units to draw — 0.05 mL × 100 units/mL = 5 units on a U-100 insulin syringe.
- Doses per vial — 10 mg ÷ 0.25 mg = 40 doses.
Enter your own numbers above to see your figures — including the reverse mode, which solves the water volume that lands your dose on a clean syringe mark.
Frequently asked questions
How much bacteriostatic water should I use to reconstitute a peptide?
There is no single right amount — the water only sets the concentration, not the dose. More water makes each unit on the syringe less concentrated (easier to measure small doses precisely); less water makes it more concentrated. Enter your vial strength and the water you plan to add and the calculator shows the exact units your prescribed dose becomes. A common choice is 2 mL of BAC water for a 10 mg vial, giving 5 mg/mL.
What does the calculator actually compute?
Concentration (vial strength ÷ water volume), the volume your dose occupies, and that volume expressed in insulin-syringe units on a U-100 (100 units = 1 mL) scale. It also estimates doses per vial and roughly how long the vial lasts, and shows the full derivation — it never recommends a dose.
What syringe unit is a 250 mcg dose of a 5 mg/mL solution?
A 250 mcg (0.25 mg) dose of a 5 mg/mL solution is 0.05 mL, which is 5 units on a U-100 insulin syringe. That 10 mg vial yields 40 such doses.
How long does a reconstituted peptide vial last?
Once mixed, most reconstituted peptides are kept refrigerated and used within a beyond-use window set by the compounder or your provider (commonly a few weeks). The calculator estimates depletion from your dose and frequency, but always follow the discard-by date on your label and your provider’s guidance.
Is this reconstitution calculator medical advice?
No. It is an educational estimation tool. It does the arithmetic from the numbers you enter and shows its work; it never prescribes, diagnoses, or recommends a dose. Always follow the instructions from your licensed provider.
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