Two things make this comparison unusual. The first is that both drugs come from the same manufacturer: Eli Lilly makes tirzepatide, sold as Zepbound, and orforglipron, sold as Foundayo since its approval on 2026-04-01. The second is that although no trial has ever compared them, their two pivotal trials are close enough in design that laying them side by side is more informative than these exercises usually are.
If you arrived searching for "Foundayo vs tirzepatide": Foundayo is orforglipron. Same drug, brand name attached at approval.
This page reports trial results, label facts and prices. It does not recommend a medicine — that decision belongs with a prescriber, as our editorial standards explain.
What each one is
Orforglipron (Foundayo) is a small-molecule, non-peptide GLP-1 receptor agonist — a conventional drug molecule rather than a modified peptide, which is why it survives digestion and can be given as a plain tablet. It is taken once daily, at any time, with or without food, swallowed whole, one tablet a day maximum. Labelled doses run 0.8, 2.5, 5.5, 9, 14.5 and 17.2 mg, escalating at intervals of at least 30 days.
Tirzepatide (Zepbound) is a peptide that activates two receptors, GIP and GLP-1. It is injected once weekly, at 2.5 mg through 15 mg, and was approved for weight management on 2023-11-08 under NDA 217806.
One is a daily pill acting on one receptor. The other is a weekly injection acting on two.
Why these two trials can almost be compared
Cross-trial comparisons usually fail because the trials differ in the ways that matter. These two differ less than most:
| Orforglipron, Trial 1 | Tirzepatide, SURMOUNT-1 | |
|---|---|---|
| Sponsor | Eli Lilly | Eli Lilly |
| Duration | 72 weeks | 72 weeks |
| Population | Obesity, or overweight plus ≥1 related condition; diabetes excluded | Obesity, or overweight plus ≥1 related condition; diabetes excluded |
| Design | Double-blind, placebo-controlled | Double-blind, placebo-controlled |
| Participants | 3,127 | 2,539 |
| Placebo arm weight change | −2.1% | −3.1% |
The placebo arms are the tell. When two trials' control groups behave similarly, the surrounding conditions — diet counselling, visit schedule, participant expectations — were probably similar too. A one-point difference between placebo arms is small.
That is a reason to take the comparison seriously. It is not a reason to treat it as a measured difference. Randomisation is what makes a comparison trustworthy, and nobody randomised anyone between these two drugs.
The results, side by side
| At week 72 | Orforglipron 17.2 mg | Tirzepatide 5 mg | Tirzepatide 10 mg | Tirzepatide 15 mg |
|---|---|---|---|---|
| Mean weight change | −11.1% | −15.0% | −19.5% | −20.9% |
| Against placebo | −2.1% | −3.1% | −3.1% | −3.1% |
| Lost ≥10% | 54.5% | — | — | — |
| Lost ≥20% | 18.4% | — | 50% | 57% |
Orforglipron figures are from the Foundayo label's Table 6 (Trial 1, NCT05869903); the same trial was published as ATTAIN-1 in the New England Journal of Medicine, where the doses are written as 6, 12 and 36 mg of an investigational formulation that the label maps onto 5.5, 9 and 17.2 mg. Tirzepatide figures are from SURMOUNT-1.
The gap is not subtle. Tirzepatide's lowest dose produced more mean weight loss than orforglipron's highest. On the proportion reaching a 20% loss — the threshold that changes how these drugs are talked about — it is 18.4% against 57%.
For people with type 2 diabetes, orforglipron's second label trial gave −9.6% at 17.2 mg against −2.5% on placebo in 1,613 participants.
How long each takes to reach its top dose
Both labels escalate slowly to limit gastrointestinal effects, and the schedules are closer than the difference in form suggests.
Foundayo starts at 0.8 mg once daily, moves to 2.5 mg after at least 30 days, then to 5.5 mg after at least another 30, and may then step to 9 mg, 14.5 mg and 17.2 mg at intervals of at least 30 days each. Five increases at 30-day minimums means at least 150 days — about five months — before anyone reaches the maximum dose.
Zepbound starts at 2.5 mg weekly for four weeks, then increases in 2.5 mg increments after at least four weeks each. From 2.5 mg to 15 mg is five increases, so at least 140 days — about the same.
The pill is not the faster route to a maintenance dose. What it does offer is an earlier useful stop: Zepbound's 2.5 mg starting dose is explicitly not approved as a maintenance dose, so the first place a tirzepatide patient can settle is 5 mg, eight weeks in. In SURMOUNT-1, that 5 mg dose produced a mean 72-week loss of 15.0% — larger than orforglipron's 11.1% at its maximum. Those are trial averages in different trials, not a forecast for any individual, but they are the numbers the two labels rest on.
Stopping, in each trial
| Orforglipron, Trial 1 | Tirzepatide, SURMOUNT-1 | |
|---|---|---|
| Stopped the trial drug, top dose | 24% | Not reported in the same form |
| Stopped the trial drug, placebo | 30% | — |
| Stopped because of adverse events | 5.3% to 10.3% across doses | 4.3%, 7.1%, 6.2% at 5, 10, 15 mg |
| Placebo, for adverse events | 2.7% | 2.6% |
Two things are worth reading here. First, more people left the orforglipron trial's placebo arm (30%) than its drug arms (22–24%), which is common in obesity trials — people who see no effect stop turning up. Second, the adverse-event discontinuation rates are broadly similar between the two drugs, in the mid-single digits to low teens. The gap between these medicines in the published record is in how much weight came off, not in how many people could tolerate them.
What the pill buys
Given that gap, the case for the tablet rests on three things that are not weight loss:
Form. No needles, no weekly schedule, no injection technique. The label imposes no food or water timing, which distinguishes it from the older oral semaglutide products.
Price at the bottom of the range. Foundayo's low doses are reported at $149 and $199 a month against Zepbound's $299 floor. At the top the two converge: $349 against $449.
A different molecule. Orforglipron is not a peptide. For anyone who has stopped a peptide GLP-1 for reasons other than the shared gastrointestinal effects, that is a real difference — though no trial has tested whether it helps.
What the pill does not buy, on any published evidence, is equivalent weight loss.
Where this comparison should go next
Lilly owns both molecules, which means it is the only party that could easily run the head-to-head, and has no commercial reason to. The gap will more likely be filled by indirect comparisons — one already exists between orforglipron and oral semaglutide, and it was written by the maker of the comparator, as our GLP-1 pills page sets out. We will update this page when a randomised comparison is registered.
Sources
- openFDA Drugs@FDA API, read 2026-09-06: FOUNDAYO NDA 220934, original approval 2026-04-01.
- FOUNDAYO prescribing information via the openFDA label API, label effective 2026-07-29: dosage and administration, boxed warning, and clinical studies Table 6 (Trials 1 and 2).
- Wharton S et al. Orforglipron, an Oral Small-Molecule GLP-1 Receptor Agonist for Obesity Treatment. N Engl J Med 2025;393(18):1796-1806. PubMed 40960239
- SURMOUNT-1 results as reported on our tirzepatide vs semaglutide page and retatrutide vs tirzepatide page, with the Zepbound approval record at Drugs@FDA, NDA 217806.
- Self-pay prices as recorded on our cost hub and GLP-1 pills page, read 2026-09-06.
- ZEPBOUND prescribing information via the openFDA label API, label effective 2026-08-28: dose escalation schedule and maintenance dosages.