Short answer: Foundayo (orforglipron) is a once-daily GLP-1 tablet taken with or without food.1 Zepbound (tirzepatide) is a once-weekly GIP and GLP-1 injection, also approved for sleep apnea in adults with obesity.2 Both are for weight loss in adults. Each label compared its drug with placebo over 72 weeks, not with the other, and both carry a thyroid C-cell tumor boxed warning.
| Foundayo | Zepbound | |
|---|---|---|
| Drug | Orforglipron, a GLP-1 receptor agonist1 | Tirzepatide, a GIP and GLP-1 receptor agonist2 |
| How taken | One tablet daily, with or without food, swallowed whole1 | Injected under the skin once a week, any time of day2 |
| Dose steps | 0.8 mg, then 2.5 mg, then 5.5 mg, at least 30 days each; may go to 9, 14.5 or 17.2 mg1 | 2.5 mg for 4 weeks, then 5 mg; up 2.5 mg after at least 4 weeks; 5, 10 or 15 mg to stay on2 |
| 72-week weight change, adults without diabetes | -11.1% on 17.2 mg vs -2.1% on placebo1 | -20.9% on 15 mg vs -3.1% on placebo2 |
| Nausea | 26% to 35% vs 10% on placebo1 | 25% to 29% vs 8% on placebo2 |
| Missed dose | Take as soon as possible, never two in a day; after 7 or more missed in a row, restart at a lower dose1 | Take within 4 days; otherwise skip and keep the usual day2 |
| Boxed warning | WARNING: RISK OF THYROID C-CELL TUMORS1 | WARNING: RISK OF THYROID C-CELL TUMORS2 |
Foundayo's Trial 1 enrolled 3,127 adults with obesity or overweight and no diabetes; at 72 weeks, weight fell 7.4%, 8.3% and 11.1% on 5.5, 9 and 17.2 mg vs 2.1% on placebo.1 Zepbound's Study 1 enrolled 2,539 similar adults; weight fell 15.0%, 19.5% and 20.9% on 5, 10 and 15 mg vs 3.1% on placebo.2 These numbers come from separate trials with different people, lengths and methods, so they are not a head-to-head comparison.
Each label has its own drug notes. Foundayo is capped at 9 mg with a strong CYP3A4 inhibitor, and simvastatin is kept at 20 mg a day or less.1 The Zepbound label advises a non-oral or added barrier contraceptive for 4 weeks after starting and after each dose increase, because it may make birth control pills work less well.2 Neither is used with another GLP-1 receptor agonist.12
Which, if either, fits is for your prescriber. More detail: Foundayo side effects, Zepbound side effects, the Foundayo and Zepbound dosing schedules, the Foundayo and Zepbound missed-dose pages, the orforglipron and tirzepatide guides, and Orforglipron vs semaglutide: how do the GLP-1 pills compare?.