Retatrutide vs Orforglipron: Triple-Agonist Injection vs GLP-1 Pill
Retatrutide and orforglipron are two of the most talked-about newer compounds in weight and metabolic research, and both come from Eli Lilly. They sit at opposite ends of the field: retatrutide is a weekly injection that acts on three receptors, while orforglipron is a daily pill that acts on one.
No trial has compared them directly yet, so this page sets their own trials side by side and explains how they differ. Everything here is educational and refers to published research. RetaNord supplies research compounds for laboratory research use only.
On this page
At a glance
| Retatrutide | Orforglipron | |
|---|---|---|
| Brand name | None yet (investigational) | Foundayo |
| Type of molecule | Peptide | Small molecule (not a peptide) |
| Receptors | GLP-1 + GIP + glucagon (triple) | GLP-1 (single) |
| Form in trials | Weekly injection | Daily tablet, no food or water restrictions |
| Main obesity trial (top dose) | TRIUMPH-1: −28.3% at 80 weeks | ATTAIN-1: −12.4% at 72 weeks |
| Stopped because of side effects (top dose vs placebo) | 11.3% vs 4.9% | 10.3% vs 2.7% |
| Status (October 2026) | Investigational, not approved in the US or the EU | Approved in the US (April 2026) and the UK (August 2026); under EMA review in the EU |
Three receptors versus one
Orforglipron is a single agonist: it activates only the GLP-1 receptor, the same target as semaglutide.
Retatrutide is a triple agonist: it activates the GLP-1, GIP and glucagon receptors. Glucagon is the extra piece; it is linked to energy use and fat metabolism in the liver, and it is the main reason retatrutide is described as a step beyond dual agonists such as tirzepatide.
A pill versus an injection
Most GLP-1 compounds are peptides: chains of amino acids that the gut would digest, so they are given by injection. Retatrutide is one of them and was given once a week in its trials.
Orforglipron is different. It is a small molecule, not a peptide, so it survives digestion and works as a once-daily tablet. Lilly states it can be taken at any time of day, with no food or water restrictions. Oral semaglutide (Rybelsus), by contrast, is a peptide tablet that has to be taken on an empty stomach.
What their trials show
- Retatrutide, TRIUMPH-1 (2026): 2,339 adults with obesity or overweight plus a weight-related condition, without diabetes. At the top dose, average body weight fell 28.3% after 80 weeks, versus 2.2% on placebo.
- Orforglipron, ATTAIN-1 (2025): 3,127 adults with obesity, without diabetes. At the top dose, average body weight fell 12.4% after 72 weeks, versus 0.9% on placebo. The results were published in the New England Journal of Medicine.
Both figures use the same type of analysis (the efficacy estimand). They come from separate trials with different people and lengths, so they are not a head-to-head comparison.
Side effects and dropouts
Both compounds share the typical GLP-1 pattern of stomach and gut side effects, mostly nausea, diarrhoea, constipation and vomiting. In the trials, the share of people who stopped treatment because of side effects at the top dose was:
- Retatrutide (12 mg): 11.3%, versus 4.9% on placebo.
- Orforglipron (36 mg): 10.3%, versus 2.7% on placebo.
Approval status in 2026
Orforglipron was approved by the US FDA on 1 April 2026 under the brand name Foundayo, for adults with obesity or overweight with weight-related conditions. The UK's MHRA authorised it on 10 August 2026, for weight management and type 2 diabetes. In the EU it is under review by the European Medicines Agency; it was still on the CHMP agenda in September 2026.
Retatrutide is still investigational and is not approved in the US or the EU. Lilly has reported several Phase 3 TRIUMPH results in 2026.
Foundayo is a trademark of Eli Lilly. RetaNord is not a pharmacy and is not affiliated with Eli Lilly. It supplies research-grade compounds for laboratory and in-vitro research use only, not for human or veterinary use.
At RetaNord
RetaNord supplies retatrutide as 10 mg research vials at €89.95, each batch with a Certificate of Analysis. Orforglipron is not part of the RetaNord range. Supplied for laboratory research use only.
Sources
- Eli Lilly – Retatrutide TRIUMPH-1 topline results, 21 May 2026
- Wharton et al. Orforglipron, an Oral Small-Molecule GLP-1 Receptor Agonist for Obesity Treatment (ATTAIN-1). N Engl J Med 2025
- Eli Lilly – Orforglipron ATTAIN-1 topline results, 16 September 2025
- Eli Lilly – FDA approves Foundayo (orforglipron), 1 April 2026
- UK MHRA – UK first in Europe to authorise orforglipron, 10 August 2026
- European Medicines Agency – CHMP agenda, 14–17 September 2026 (orforglipron, EMEA/H/C/006632)
Frequently asked questions
Is retatrutide stronger than orforglipron?
No trial has compared them directly. In their own main trials, retatrutide reached about 28% average weight loss at 80 weeks and orforglipron about 12% at 72 weeks, at their top doses.
What is Foundayo?
Foundayo is the brand name of orforglipron, a once-daily GLP-1 pill from Eli Lilly. The US FDA approved it on 1 April 2026.
Is orforglipron approved in Europe?
The UK authorised it in August 2026. In the EU it was still under review by the European Medicines Agency in September 2026.
Is retatrutide approved?
No. Retatrutide is still investigational and is not approved in the US or the EU.