Definition: Reconstitution is adding a liquid, called a diluent, to a powdered drug so it dissolves into a solution that can be drawn into a syringe. Many peptide and hormone products ship as a dry powder because they keep better that way. The volume of liquid you add decides how strong the solution is.
How approved labels describe it
Labels for powdered products spell out the diluent, the volume and how to handle the vial. The Omnitrope (somatropin) label says to swirl gently after adding the diluent and not to shake, because shaking may denature (damage) the protein. After mixing, the label concentration is 5 mg/mL.
Some labels let you choose the volume, and the choice changes the strength. Novarel (hCG) lists two options for its 10,000-unit vial:
Novarel 10,000 USP unit vial, per the label.
| Diluent added | Concentration | Label use |
|---|
| 1 mL | 10,000 units/mL | Single dose |
| 10 mL | 1,000 units/mL | Multiple doses, refrigerated between doses |
Worked example
The drug in the vial never changes. Only the liquid does. Here is one 10 mg vial mixed three ways, read on a U-100 insulin syringe (1 mark = 0.01 mL):
One 10 mg vial, three water volumes
- 1 mL: 10 mg ÷ 1 mL = 10 mg/mL. Per mark: 10 × 0.01 = 0.1 mg = 100 mcg.
- 2 mL: 10 mg ÷ 2 mL = 5 mg/mL. Per mark: 5 × 0.01 = 0.05 mg = 50 mcg.
- 3 mL: 10 mg ÷ 3 mL = 3.33 mg/mL. Per mark: about 33.3 mcg.
- The same 10 units on the syringe means 1,000, 500 or 333 mcg depending on how the vial was mixed.
This is why the mix volume and date belong with the vial in your log. Dose Track saves each vial with its mix date and concentration, and the reconstitution calculator runs the math above.
Common mix-ups
- Remixing a new vial with a different volume and keeping the old units. The units must be worked out again.
- Shaking the vial. Labels for protein drugs say to swirl gently.
- Forgetting the clock. Each approved label gives a limit after mixing, such as 30 days refrigerated for Novarel and 21 days for the Omnitrope vial.
Read more on Dose Track: Peptide reconstitution calculator · How long mixed peptides last · hCG guide
General education drawn from labels and published studies, not personal medical advice. Your prescriber, pharmacist and the label that came with your product are the final word.
Does adding more water make the dose weaker?+
It makes each mL weaker, so you draw more volume for the same amount of drug. The total amount in the vial does not change.
Should I shake a vial to mix it?+
Labels for protein drugs such as Omnitrope say to swirl gently and not to shake, because shaking may damage the protein.
How long does a reconstituted vial last?+
It depends on the product. Approved labels give tested limits, for example 30 days refrigerated for Novarel hCG and 21 days for the Omnitrope vial.