For tirzepatide labeled 2.5 mg/0.5 mL, 2.5 mg is 50 units on a U-100 insulin syringe.
The correct syringe marking depends on the product's concentration:
| Tirzepatide concentration | Volume for 2.5 mg | U-100 syringe marking |
|---|---|---|
| 2.5 mg/0.5 mL | 0.5 mL | 50 units |
| 2.5 mg/0.6 mL | 0.6 mL | 60 units |
| 10 mg/mL | 0.25 mL | 25 units |
FDA-approved single-dose Mounjaro and Zepbound presentations contain 2.5 mg in 0.5 mL, which equals 50 units on a U-100 syringe. Some Mounjaro multi-dose presentations contain 2.5 mg in 0.6 mL, which equals 60 units.
Check the Concentration on Your Vial
Use this formula:
Units = prescribed dose in mg ÷ concentration in mg/mL × 100
"Units" measure liquid volume on a U-100 syringe. Milligrams alone do not determine the number of units. This is especially important with compounded tirzepatide, which may be prepared at different concentrations. The FDA has warned that confusion between milligrams, milliliters and syringe units has caused dosing errors.
If your vial or pharmacy instructions do not clearly state the concentration, do not inject until your pharmacist or prescriber confirms the exact syringe marking.
Mounjaro and Zepbound pens deliver a preset dose. Do not convert a pen dose to syringe units.