At a glance
| Concentration | 12.5 mg is | Mark on U-100, 1 mL |
|---|---|---|
| 4.17 mg/mL Zepbound 10 mg multi-dose vial | 2.998 mL | does not fit (over 1 mL) |
| 5 mg/mL Zepbound 2.5 mg single-dose vial | 2.5 mL | does not fit (over 1 mL) |
| 8.33 mg/mL Zepbound 20 mg multi-dose vial | 1.501 mL | does not fit (over 1 mL) |
| 10 mg/mL Zepbound 5 mg single-dose vial | 1.25 mL | does not fit (over 1 mL) |
| 12.5 mg/mL Zepbound 30 mg multi-dose vial | 1 mL | 100 |
| 16.7 mg/mL Zepbound 40 mg multi-dose vial | 0.749 mL | 75 (exactly 74.85) |
| 20 mg/mL Zepbound 10 mg single-dose vial | 0.625 mL | 63 (exactly 62.5) |
| 25 mg/mL Zepbound 12.5 mg single-dose vial and 60 mg multi-dose vial | 0.5 mL | 50 |
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 vial
12.5 mg is drawn to the 50 mark from the 12.5 mg single-dose vial (25 mg/mL, the whole 0.5 mL) and to the 60 mark from the 50 mg multi-dose vial (20.8 mg/mL, one of four 0.6 mL withdrawals). The multi-dose concentration for this strength is printed as 20.8 mg/mL, a rounded figure; 50 mg in 2.4 mL is 20.83. That rounding is why the calculator shows 12.48 mg for a 0.6 mL draw rather than exactly 12.5, and why it does not flag the labelled withdrawal as a mismatch. If you are checking by hand and get 12.48, you have done it right. At 25 mg/mL, the single-dose concentration, 12.5 mg is exactly 0.5 mL and there is nothing to round.
The mistake to watch for. At 25 mg/mL the 12.5 mg single-dose vial and the 60 mg multi-dose vial share a concentration. A 12.5 mg dose is 0.5 mL from either, the 50 mark, but from the multi-dose vial the label describes 0.6 mL withdrawals of 15 mg. Same concentration, different labelled dose; the vial's own instructions decide which draw is described.