Peptide reconstitution calculator.

The formula behind the number

Reconstitution math is two steps. First you find the concentration of the reconstituted vial, then you find the volume that carries the dose. The syringe reading is a third step only because insulin syringes are marked in units rather than millilitres.

1. Concentration (mg/mL) = vial strength in mg ÷ bacteriostatic water in mL.
2. Volume (mL) = dose in mg ÷ concentration in mg/mL. A dose given in mcg is divided by 1,000 first.
3. Units on a U-100 syringe = volume in mL × 100.

A worked example

A 5 mg vial reconstituted with 2 mL of bacteriostatic water, against a 250 mcg dose set by a healthcare professional:

So the draw is to the 10 unit mark. Change the water volume and the mark moves: the same 5 mg vial reconstituted with 1 mL instead gives 5 mg/mL, and the same 250 mcg dose lands at 5 units. The dose count does not move with it: the vial holds 20 doses of 250 mcg either way, which the peptide dosage calculator works out alongside the draw.

How to reconstitute a vial

1. 1
   Read the vial's total strength

   The label shows total peptide in the vial, in mg. It is the whole vial, not one dose.

2. 2
   Set the bacteriostatic water volume

   This volume, set with your healthcare professional, fixes concentration. More water gives a lower, easier draw.

3. 3
   Add the bacteriostatic water slowly

   Aim the stream at the vial wall, not the powder, since peptides are fragile in solution. The full reconstitution guide walks through each step.

4. 4
   Let it dissolve without shaking

   Swirl gently or simply wait. Agitation is generally avoided.

5. 5
   Calculate the draw in units

   Divide strength by water for concentration, divide dose by that, then multiply by 100 for units.

6. 6
   Record the reconstitution for later

   Strength, water volume, and date make every later dose calculable. Peptmate stores this setup once.

Common reasons the number looks wrong

• Dose entered in mg instead of mcg. A 250 in the mcg field is 0.25 mg. A 250 in a mg field would be a thousandfold different. How mg, mcg, mL and units connect.
• Vial strength read as a per-dose amount. The mg on the label is the whole vial.
• A syringe that is not U-100. A U-40 barrel uses a different scale, so the × 100 step does not apply. The insulin syringe unit converter shows how a U-100 barrel reads.
• Water volume estimated rather than measured. The concentration is only as accurate as the diluent volume, and every later draw inherits that error. The bacteriostatic water calculator shows how much each millilitre moves the draw.
• Switching syringe size moved the number. It shouldn't. 30, 50 and 100 unit barrels all read 100 units per mL, so the mark for a dose is the same on each. The size only decides whether the draw fits in the barrel.