At a glance
| Concentration | 2.5 mg is | Mark on U-100, 1 mL |
|---|---|---|
| 4.17 mg/mL Zepbound 10 mg multi-dose vial | 0.6 mL | 60 (exactly 59.95) |
| 5 mg/mL Zepbound 2.5 mg single-dose vial | 0.5 mL | 50 |
| 8.33 mg/mL Zepbound 20 mg multi-dose vial | 0.3 mL | 30 (exactly 30.01) |
| 10 mg/mL | 0.25 mL | 25 |
| 12.5 mg/mL Zepbound 30 mg multi-dose vial | 0.2 mL | 20 |
| 20 mg/mL | 0.125 mL | 13 (exactly 12.5) |
Arithmetic at the concentrations shown. The concentration on your own label is the one that counts; enter it in the calculator.
Why the answer depends on the label
Tirzepatide is the medication in Zepbound and Mounjaro, and 2.5 mg is the lowest strength on both labels. Whether that dose is 50 units or 60 units or something else depends entirely on which vial is in front of you. Zepbound single-dose vials contain one labelled dose in 0.5 mL of liquid, so for a 2.5 mg prescription and a 2.5 mg vial, the draw is everything in the vial: 0.5 mL, the 50 mark on a U-100 1 mL syringe. Zepbound multi-dose vials hold four doses in 2.4 mL, and the label describes each withdrawal as 0.6 mL, which is the 60 mark. The 10 mg multi-dose vial is 4.17 mg/mL, so 0.6 mL of it is 2.5 mg. Compounded tirzepatide vials are not FDA-approved products, and their concentration varies by dispensing pharmacy. For those, the mg/mL on your own pharmacy label is the number that counts. The table shows the arithmetic at the labelled Zepbound concentrations and at two other values purely as examples.
The mistake to watch for. Drawing a 2.5 mg dose out of a higher-strength single-dose vial is not the same question. A single-dose vial is one dose, and splitting it involves stability and sterility questions this calculator does not address. The question for your pharmacist is whether the label describes drawing part of this vial at all.