Retatrutide: Research Guide, Identity, Trial Status and COA (USA)

Researched & reviewed by the Purity Collective Quality Team · Last reviewed October 1, 2026

Compound guide · Retatrutide

Retatrutide (development code LY3437943) is a single peptide that activates three receptors: GIP, GLP-1 and glucagon. It is an investigational drug in phase 3 trials and is not approved by the FDA for any use. This guide sets out its identity checked against PubChem, the receptor rationale, how the clinical program is designed, the preclinical record, what the evidence does not show, and what Purity Collective’s lot reports cover for each of its five listings.

For laboratory research only. Not for human or animal use. Retatrutide is an unapproved investigational compound; nothing here is medical, dosing, weight-loss or administration advice.

How to choose a retatrutide listing

Purity Collective lists retatrutide in four vial sizes and one pen. Four of the five have a posted lot report; the 20mg vial does not. The pen shares the 10mg vial’s lot.

Three receptors in one molecule

The incretin-drug field moved in steps: first GLP-1 receptor agonists, then dual GIP/GLP-1 agonists such as tirzepatide, then compounds that add glucagon receptor activity. Each receptor was added for a different reason. GLP-1 receptor activation lowers glucose and food intake; the GIP receptor arm became a target in its own right once mouse work linked GIPR agonism to weight-independent insulin sensitization by tirzepatide^[34003802], and tirzepatide itself turned out to be an imbalanced agonist favoring the GIP receptor^[32730231]. Glucagon receptor activation raises energy expenditure and acts on the liver.

The discovery paper for LY3437943 described a peptide with balanced glucagon and GLP-1 receptor activity and stronger GIP receptor activity in vitro. In obese mice it lowered body weight and improved glycemic control, and the authors attributed the extra weight effect to glucagon-receptor-driven energy expenditure added to GIP- and GLP-1-driven reductions in intake; the same paper reported a single ascending dose study in people with a tolerability profile similar to other incretins and a pharmacokinetic profile long enough for weekly intervals^[35985340]. Cryo-electron microscopy structures later showed how one peptide engages all three receptors^[39019866].

Chemical identity

Checked against PubChem on October 1, 2026, not copied from a lot report.

The clinical program, described neutrally

This section describes trial designs, populations and endpoints so that the literature can be located and read. It deliberately does not repeat effect sizes: retatrutide is unapproved, and trial results are not claims about the research material sold here.

Phase 1 and phase 2

A 12-week phase 1b trial in adults with type 2 diabetes had safety and tolerability as its primary outcome, with pharmacokinetics and pharmacodynamics as secondary outcomes, and included placebo and dulaglutide arms^[36354040]. Two 2023 phase 2 trials followed: a 48-week placebo-controlled study in adults with obesity whose primary endpoint was percentage change in body weight at 24 weeks^[37366315], and a 36-week placebo- and dulaglutide-controlled study in type 2 diabetes whose primary endpoint was change in HbA1c at 24 weeks^[37385280]. In the obesity trial the most common adverse events were gastrointestinal, dose-related and mostly mild to moderate^[37366315]. Substudies of those trials examined liver fat in metabolic dysfunction-associated steatotic liver disease^[38858523] and body composition by DXA^[40609566].

Phase 3

The TRIUMPH program is a set of phase 3, randomized, double-blind, placebo-controlled trials in more than 5,800 participants, using a basket design that nests knee osteoarthritis and obstructive sleep apnea protocols inside weight-management trials^[41090431]. In 2026 three phase 3 reports were published: a 40-week monotherapy trial in type 2 diabetes with change in HbA1c as the primary endpoint^[42250575]; TRIUMPH-2 in adults with obesity and type 2 diabetes^[42810372]; and an 80-week trial in adults with obesity without diabetes whose primary outcomes were body weight, a knee osteoarthritis pain score and the apnea-hypopnea index in the relevant subgroups^[42814954]. Regulatory review is a separate step that had not concluded as of this guide’s review date.

Preclinical and laboratory work

Beyond the discovery work in obese mice^[35985340], two recent laboratory studies show the kind of questions researchers are asking. In isolated mouse atria, retatrutide did not increase force of contraction in left atrial preparations but raised beating rate in right atrial preparations, an effect blocked by a glucagon receptor antagonist^[40464942], which points to the glucagon arm when studying heart-rate effects. In mouse models of kidney fibrosis (unilateral ureteral obstruction and aging) and in HK-2 kidney cells, semaglutide, tirzepatide and retatrutide each showed model- and drug-specific pathway patterns^[42630988]. Both are animal or tissue studies and say nothing on their own about people.

Study table

What the evidence does not show

• No approval. Retatrutide has no FDA approval for any condition; trial results describe a regulated investigational product under medical supervision, not research-grade material.
• No long-term outcome data. The published trials run 12 to 80 weeks and measure intermediate endpoints such as body weight, HbA1c, liver fat or pain scores^{[37366315][42250575][42814954]}. Cardiovascular-outcome and multi-year safety results are not yet in the published record.
• Tolerability is not trivial. Gastrointestinal adverse events were the most common and were dose-related^[37366315], and laboratory work links the glucagon arm to heart-rate effects in mouse atria^[40464942].
• Animal comparisons are not head-to-head human data. The three-drug kidney study is a mouse and cell study^[42630988].
• Nothing here supports any use of research material in people or animals.

Batch documentation

Retatrutide 10mg, lot PCCL-5859103-P (Horizon Analytical, analysis June 11, 2026, UPLC/MS): 9.97mg against a 10mg specification, purity 99.34%; endotoxin report PCCL-5859103-E reads <0.05 EU/mL. The pen links the same lot. Purity’s media library also holds reports for an earlier 10mg lot, PCCL-6141790 (April 2026), whose endotoxin result was 0.061 EU/mL; this guide quotes the current lot, PCCL-5859103.

Retatrutide 15mg, lot PCCL-5244055-P (Horizon, June 11, 2026): 14.76mg against 15mg, purity 99.39%; endotoxin <0.05 EU/mL (PCCL-5244055-E). Retatrutide 30mg, lot PCCL-1857910-P (Horizon, May 4, 2026): 29.75mg against 30mg, purity 99.42%; endotoxin <0.05 EU/mL (PCCL-1857910-E).

Retatrutide 20mg: a batch COA for this product isn’t posted yet. No certificate for another strength should be read as documenting the 20mg vial.

All reports print the formula C221H342N46O68 and PubChem CID 171390338, which match the PubChem record above. The PDFs are in the COA library; for what each field means see how to read a peptide COA.

Handling and storage in the laboratory

Vials are lyophilized powder; keep them cold, dry and away from light until use. The pen holds a liquid formulation and should be stored refrigerated as stated on the product page. Record the lot number with each experiment so a result traces back to its certificate. Purity Collective publishes no reconstitution, dosing or administration instructions for any product.

Frequently asked questions

References

1. Coskun T, Urva S, Roell WC et al. LY3437943, a novel triple glucagon, GIP, and GLP-1 receptor agonist for glycemic control and weight loss: From discovery to clinical proof of concept. Cell Metab. 2022;34:1234-1247.e9. PMID 35985340 · doi:10.1016/j.cmet.2022.07.013
2. Li W, Zhou Q, Cong Z et al. Structural insights into the triple agonism at GLP-1R, GIPR and GCGR manifested by retatrutide. Cell Discov. 2024;10:77. PMID 39019866 · doi:10.1038/s41421-024-00700-0
3. Urva S, Coskun T, Loh MT et al. LY3437943, a novel triple GIP, GLP-1, and glucagon receptor agonist in people with type 2 diabetes: a phase 1b, multicentre, double-blind, placebo-controlled, randomised, multiple-ascending dose trial. Lancet. 2022;400:1869-1881. PMID 36354040 · doi:10.1016/S0140-6736(22)02033-5
4. Jastreboff AM, Kaplan LM, Frías JP et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity – A Phase 2 Trial. N Engl J Med. 2023;389:514-526. PMID 37366315 · doi:10.1056/NEJMoa2301972
5. Rosenstock J, Frias J, Jastreboff AM et al. Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a randomised, double-blind, placebo and active-controlled, parallel-group, phase 2 trial conducted in the USA. Lancet. 2023;402:529-544. PMID 37385280 · doi:10.1016/S0140-6736(23)01053-X
6. Sanyal AJ, Kaplan LM, Frias JP et al. Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatotic liver disease: a randomized phase 2a trial. Nat Med. 2024;30:2037-2048. PMID 38858523 · doi:10.1038/s41591-024-03018-2
7. Coskun T, Wu Q, Schloot NC et al. Effects of retatrutide on body composition in people with type 2 diabetes: a substudy of a phase 2, double-blind, parallel-group, placebo-controlled, randomised trial. Lancet Diabetes Endocrinol. 2025;13:674-684. PMID 40609566 · doi:10.1016/S2213-8587(25)00092-0
8. Giblin K, Kaplan LM, Somers VK et al. Retatrutide for the treatment of obesity, obstructive sleep apnea and knee osteoarthritis: Rationale and design of the TRIUMPH registrational clinical trials. Diabetes Obes Metab. 2026;28:83-93. PMID 41090431 · doi:10.1111/dom.70209
9. Bajaj HS, Welch M, Shah P et al. Efficacy and safety of retatrutide, a GIP, GLP-1, and glucagon receptor agonist, in people with type 2 diabetes and inadequate glycaemic control with diet and exercise (TRANSCEND-T2D-1): a double-blind, randomised, phase 3 trial. Lancet. 2026;407:2402-2413. PMID 42250575 · doi:10.1016/S0140-6736(26)00967-0
10. Bellido V, le Roux CW, Ekinci EI et al. Retatrutide in adults with obesity and type 2 diabetes (TRIUMPH-2): a double-blind, parallel-group, randomised, placebo-controlled, phase 3 trial. Lancet. 2026. PMID 42810372 · doi:10.1016/S0140-6736(26)01861-1
11. Jastreboff AM, Kaplan LM, Davies MJ et al. Retatrutide, a Triple Hormone Receptor Agonist, for Treatment of Obesity. N Engl J Med. 2026. PMID 42814954 · doi:10.1056/NEJMoa2604169
12. Ding M, Li X, Wei Y et al. Comparative effects of semaglutide tirzepatide and retatrutide on renal fibrosis in UUO and aged mice. iScience. 2026;29:117174. PMID 42630988 · doi:10.1016/j.isci.2026.117174
13. Neumann J, Ahlrep U, Hofmann B et al. Contractile effects of retatrutide in isolated mouse atrial preparations. Naunyn Schmiedebergs Arch Pharmacol. 2025;398:17147-17160. PMID 40464942 · doi:10.1007/s00210-025-04335-0
14. Samms RJ, Christe ME, Collins KA et al. GIPR agonism mediates weight-independent insulin sensitization by tirzepatide in obese mice. J Clin Invest. 2021;131. PMID 34003802 · doi:10.1172/JCI146353
15. Willard FS, Douros JD, Gabe MB et al. Tirzepatide is an imbalanced and biased dual GIP and GLP-1 receptor agonist. JCI Insight. 2020;5. PMID 32730231 · doi:10.1172/jci.insight.140532

Related reading

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