Retatrutide (LY3437943) is an investigational triple agonist that engages the GLP-1, GIP and glucagon receptors simultaneously. In Phase 3 trials it produced up to 28.3% average weight reduction — the strongest result ever published for an obesity pharmacotherapy candidate.
Retatrutide is a once-weekly investigational peptide developed by Eli Lilly. Where semaglutide activates one metabolic hormone receptor and tirzepatide two, retatrutide is the only late-stage candidate to activate three: GLP-1, GIP and the glucagon receptor.
The glucagon component is what sets it apart in the research literature — rather than only reducing energy intake through appetite pathways, it also raises energy expenditure and drives fat oxidation in the liver. Researchers describe it as working on both sides of the energy equation, and Phase 2 sub-studies recorded striking reductions in liver fat alongside the weight data.
Retatrutide remains investigational worldwide and is not an approved medicine. It is supplied strictly as a reference material for laboratory research.
Findings from the published literature, with the evidence level stated honestly for every claim.
Phase 3 TRIUMPH-1 (2026): average reduction at 80 weeks on the 12 mg arm — the largest reported in any obesity drug trial.
Phase 3 · humanThe only late-stage candidate engaging GLP-1, GIP and glucagon receptors at once — reducing intake and raising energy expenditure.
MechanismShare of 12 mg participants in TRIUMPH-1 reaching a range historically associated with bariatric surgery.
Phase 3 · human| Compound | Retatrutide (LY3437943) |
|---|---|
| CAS number | 2381089-83-2 |
| Class | GIP / GLP-1 / glucagon triple receptor agonist |
| Content | 40 mg — lyophilised vial or pre-filled pen |
| Purity | ≥99% (HPLC) — batch COA supplied |
| Form | Lyophilised powder / solution cartridge (pen) |
| Storage | 2–8 °C, protected from light. Never freeze pens. |
Lyophilised vials: store refrigerated at 2–8 °C (freezer for long-term), protected from light. Reconstitute with bacteriostatic water and swirl gently — never shake. Pens and reconstituted solution must be kept at 2–8 °C and never frozen; freezing permanently degrades the peptide.
The vial contains lyophilised (freeze-dried) powder for reconstitution in a laboratory setting. The pen contains the compound in solution in a dial-dose cartridge format. Both are supplied with batch-matched third-party certificates of analysis.
No. Retatrutide is an investigational compound in Phase 3 clinical development. It is not a licensed medicine in the UK or anywhere else, and PMR PHARMA supplies it strictly for laboratory research.
Every batch is tested by an independent third-party laboratory using HPLC for purity and mass spectrometry for identity. The certificate of analysis for your batch number is available on request via WhatsApp.
Refrigerate at 2–8 °C immediately. Vials tolerate brief ambient transit; pens should go straight into refrigeration and must never be frozen.
Message us on WhatsApp for availability, batch COAs and dispatch. A real person replies — usually within the hour.
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