Orforglipron (Foundayo)

What orforglipron is

The weight-loss injections of recent years, above all semaglutide and tirzepatide, are peptides, that is, delicate protein molecules that the stomach would break down. That is why they are injected. The semaglutide tablet gets around this with an excipient but has to be taken on an empty stomach with a little water. Orforglipron takes a different route: it is a classic small molecule, chemically built and acid-stable, that nonetheless activates the GLP-1 receptor.

For a long time, this receptor was considered too complex for small molecules. Orforglipron was discovered by the Japanese company Chugai and developed by Eli Lilly. Pharmacologists describe it as a biased partial agonist that preferentially switches on certain signaling pathways of the receptor. In practice, this means: one tablet a day, at any time of day, regardless of meals, and no cold chain.

How it works

The GLP-1 receptor is a central switch for satiety and blood sugar. When it is activated, insulin release after meals increases, the stomach empties more slowly, and the brain signals satiety earlier. As a result, people eat less without having to force themselves. As with the injections, the dose is increased step by step, because the body needs time to get used to the effect on the gastrointestinal tract.

Besides weight, waist circumference, systolic blood pressure, triglycerides and non-HDL cholesterol improved in ATTAIN-1 compared with placebo. These are risk markers for the heart and blood vessels. Whether fewer heart attacks and strokes also follow, as has been shown for semaglutide as an injection, is still open for orforglipron.

Tablet or injection

Above all, the tablet lowers one hurdle: many people do not want to inject themselves permanently. Add to that simple storage, suitability for travel and the prospect of cheaper mass production. On the other hand, a daily tablet is easier to forget than a weekly injection. There is no direct comparison with the weight-loss injections. An indirect comparative analysis, funded by the manufacturer of the semaglutide tablet, saw the highest dose of the semaglutide tablet ahead on weight, while orforglipron has a clear advantage in how it is taken.

For preserving muscle, the same applies as with any GLP-1 therapy. Anyone who loses a lot of weight quickly also loses muscle mass; strength training and enough protein counteract this. And anyone who stops the drug without changing habits must expect appetite to return and with it part of the weight.

What the studies show

ATTAIN-1, New England Journal of Medicine 2025

Wharton and colleagues randomized 3,127 adults with obesity without diabetes to 3 doses of orforglipron or placebo, each with nutrition and exercise counseling, over 72 weeks. Weight fell by 7.5, 8.4 and 11.2 percent, versus 2.1 percent on placebo. 5.3 to 10.3 percent of participants on orforglipron stopped because of side effects, versus 2.7 percent on placebo. The most common side effects affected the gastrointestinal tract and were mostly mild to moderate.

ACHIEVE-1 in early type 2 diabetes, 2025

Rosenstock and colleagues studied 559 people with type 2 diabetes treated with diet and exercise alone, over 40 weeks. From a baseline HbA1c of 8.0 percent, the value fell by 1.24 to 1.48 percentage points on orforglipron, versus 0.41 on placebo. Weight fell by 7.6 percent at the highest dose, versus 1.7 percent. No severe hypoglycemia occurred.

ACHIEVE-3 versus the semaglutide tablet, Lancet 2026

In this open-label trial in 1,698 people with type 2 diabetes on metformin, orforglipron was pitted against the semaglutide tablet over 52 weeks. Both orforglipron doses lowered HbA1c more than both semaglutide doses, at the highest dose by 1.91 percentage points versus 1.47. Gastrointestinal complaints were more frequent, at 58 to 59 percent versus 37 to 45 percent, as were discontinuations because of side effects, at 9 to 10 percent versus 4 to 5 percent, and heart rate rose more.

Where the data stop

What is missing are hard endpoints. The trials measure weight, blood sugar and risk markers, not heart attacks, strokes or mortality. Such outcome trials are under way, and a 2026 review explicitly calls the cardiovascular question open, partly because of the particular action profile as a partial agonist. Safety data so far extend to 104 weeks; longer courses are still missing.

Caution is needed when comparing with other drugs. The direct comparison with the semaglutide tablet was in type 2 diabetes and was open-label, not blinded. For weight in obesity, there are only indirect comparisons: an analysis funded by the manufacturer of the semaglutide tablet, based on data from two separate trials, saw the highest dose of the semaglutide tablet 3.2 percentage points ahead and more discontinuations with orforglipron. Such analyses do not replace a direct trial. The figure of 12.4 percent comes from the manufacturer's communications and describes only participants who stayed on treatment; the analysis of everyone randomized gives 11.2 percent.

Status, approval and legal

In the US, the FDA approved orforglipron on April 1, 2026 under the name Foundayo, for adults with obesity and for certain adults with overweight and weight-related comorbidities. According to Lilly, the drug has been submitted in more than 40 countries. The United Kingdom approved orforglipron in August 2026 as the first European country. In the EU, there was no recommendation for approval up to the CHMP meeting in September 2026; orforglipron is therefore not available in Germany, and dosage information is omitted here. Offers from the internet carry a high risk of counterfeits for such a new drug. Orforglipron is not on the WADA Prohibited List.

Safety

The side effect profile matches that of the GLP-1 class: nausea, constipation, diarrhea, vomiting and indigestion, mostly mild to moderate and mainly in the phase of dose escalation. In ATTAIN-1, 5.3 to 10.3 percent stopped because of side effects. Compared with the semaglutide tablet, gastrointestinal complaints and increases in heart rate were more frequent on orforglipron. A pooled analysis across 11,220 participants and up to 104 weeks found no cases meeting the criteria for drug-induced liver injury; liver values even fell on average. The known precautions for the class apply here too, for example in pregnancy and with a history of pancreatitis. The therapy belongs in medical hands.

Sources

• Wharton S et al., New England Journal of Medicine 2025 — ATTAIN-1, 3,127 participants, 72 weeks
• Rosenstock J et al., New England Journal of Medicine 2025 — ACHIEVE-1 in early type 2 diabetes
• Rosenstock J et al., Lancet 2026 — ACHIEVE-3 versus the semaglutide tablet
• Wharton S et al., Diabetes, Obesity and Metabolism 2026 — pooled liver safety from 7 phase 3 trials
• Michalak W et al., Diabetes, Obesity and Metabolism 2026 — indirect comparison with the semaglutide tablet
• Guo J, Chen H, Frontiers in Pharmacology 2026 — review of oral small-molecule GLP-1 agonists
• Eli Lilly, press release of April 1, 2026 — FDA approval of Foundayo
• European Medicines Agency, CHMP meeting September 14–17, 2026
• MHRA, announcement of August 10, 2026 — approval of orforglipron in the United Kingdom