Peptide reconstitution calculator, vial content + diluent → concentration

The formula

Concentration = total peptide in vial ÷ diluent volume

Expressed per tenth of a millilitre: concentration ÷ 10 = amount per 0.1 mL. Both describe the prepared solution itself, independent of how any volume of it is subsequently measured or handled.

Worked example, BPC-157, 5 mg vial

Vial: 5 mg (5000 mcg) lyophilized BPC-157
Diluent: 2 mL bacteriostatic water added
Concentration: 2500 mcg/mL
Per 0.1 mL: 250 mcg

Common reference values

5 mg vial + 2 mL diluent: 2500 mcg/mL · 250 mcg per 0.1 mL
5 mg vial + 1 mL diluent: 5000 mcg/mL · 500 mcg per 0.1 mL
10 mg vial + 2 mL diluent: 5000 mcg/mL · 500 mcg per 0.1 mL
2 mg vial + 1 mL diluent: 2000 mcg/mL · 200 mcg per 0.1 mL

Notes on reconstituted solutions

Diluent volume and concentration move inversely: halving the diluent doubles the concentration for the same vial.
Concentration is a property of the solution, not of any particular measurement of it.
For NAD+ and AOD-9604 the reported reconstituted shelf life is shorter, 30 to 45 days against a typical 60 to 90.

Reported research figures only. Not a clinical recommendation. Consult a qualified clinician before any human use.

Open the interactive PeptideHelper.org reconstitution calculator to enter the vial content and diluent volume and read the resulting concentration.

Frequently asked questions

How do I calculate the concentration of a reconstituted peptide vial?

Concentration = total peptide in the vial ÷ diluent volume. A 5 mg BPC-157 vial reconstituted with 2 mL of bacteriostatic water is 2500 mcg/mL, which is 250 mcg per 0.1 mL. Dividing the concentration by ten expresses it per tenth of a millilitre.

How does diluent volume affect concentration?

Inversely. 1 mL and 2 mL are the volumes most commonly reported. A larger diluent volume lowers the concentration of the resulting solution; a smaller volume raises it. The peptide content of the vial is unchanged either way.

What is BAC water?

Bacteriostatic water (Bacteriostatic Water for Injection, USP) is sterile water containing 0.9% (9 mg/mL) or 1.1% (11 mg/mL) benzyl alcohol as a bacteriostatic preservative, supplied in multiple-dose vials. The preservative is what allows repeated withdrawals from one vial, which is why it is the diluent reported for lyophilized peptides in multi-dose research use. The label states it is not for use in neonates.

Sources: Pfizer (Hospira), Bacteriostatic Water for Injection, USP, prescribing information.

How do I convert between mcg and mg?

1 mg is 1,000 mcg. A 5 mg vial holds 5,000 mcg, and 250 mcg is 0.25 mg. The calculator accepts the vial content in either unit and converts internally, so a concentration reads the same whichever unit is entered.

How long does a reconstituted peptide last?

Refrigerated, a reconstituted peptide is reported to keep up to 60-90 days (30-45 for NAD+ and AOD-9604). Before reconstitution, lyophilized powder is reported stable for up to 1 year refrigerated and 2-3 years frozen. Figures from PeptideHelper.org's handling and storage guide.