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Research Overview • 27 April 2026 • 8 min read

Retatrutide: Triple Receptor Agonism and Phase 3 Clinical Development

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A summary of published research on retatrutide (LY3437943), a synthetic peptide under Phase 3 investigation as the first triple GIP/GLP-1/glucagon receptor agonist in clinical trials. For research purposes only — not for human therapeutic use.

EP
Eternal Peptides Wholesale Research Team
Published 27 April 2026 · Updated September 2026 · For research use only

What Is Retatrutide?

Retatrutide (LY3437943) is a synthetic peptide developed by Eli Lilly and studied as an agonist at GIP, GLP-1 and glucagon receptors. Its receptor mechanism and clinical development are described in the studies cited below.

Triple Receptor Mechanism

GLP-1R Agonism

GLP-1 receptor activation is involved in glucose-dependent insulin secretion, glucagon regulation, gastric emptying and energy intake.

GIPR Agonism

GIP receptor activity is studied in insulin secretion and adipose-tissue metabolism.

GCGR Agonism — The Distinguishing Mechanism

Glucagon receptor activity is studied in hepatic glucose regulation and energy metabolism. The net effects of a multi-receptor agonist must be established experimentally.

Phase 2 Published Data

Results published in the New England Journal of Medicine (Jastreboff et al., 2023) from a randomised Phase 2 trial across dose cohorts (1mg, 4mg, 8mg, 12mg once weekly) showed:

  • ~24% mean body weight reduction from baseline at 48 weeks in the highest dose cohort
  • Dose-dependent reductions in liver fat fraction (MRI-PDFF), triglycerides, and systolic blood pressure
  • Adverse events consistent with GLP-1 class — predominantly gastrointestinal, dose-dependent

Source: Jastreboff AM et al. N Engl J Med. 2023;389(6):514-526. Phase 2 data only.

Phase 3 Programme: TRIUMPH Trials

TRIUMPH-1: evidence update, 29 September 2026

Lilly presented TRIUMPH-1 Phase 3 results at the ADA Scientific Sessions on 6 June 2026, with an 80-week primary assessment and a 104-week extension. These findings are separate from the 2023 Phase 2 study and do not establish equivalence of separately supplied research materials.

Source: Lilly: TRIUMPH-1, ADA 2026. Consult individual trial records for other populations and endpoints; this is not a complete programme inventory.

Available for Laboratory Research

For practical sourcing checks, see our guide to Retatrutide suppliers and laboratory reports.

Eternal Peptides Wholesale is one of Australia's only dedicated wholesale research peptide suppliers supplying Retatrutide with published Kovera Labs reports for laboratory research.

Retatrutide is listed by Eternal Peptides Wholesale for laboratory research. Kovera Labs reports for each Retatrutide strength and batch (RT10 and RT20) cover purity and identity, endotoxin, heavy metals and sterility.

Retatrutide 10mg — View Product Retatrutide 20mg — View Product

Frequently Asked Questions

What is retatrutide?
Retatrutide (LY3437943) is an investigational triple GIP/GLP-1/glucagon receptor agonist in Phase 3 clinical trials. It is the first triple incretin agonist to enter large-scale trials. Available as a research peptide from Eternal Peptides Wholesale for qualified laboratory use only.
Is retatrutide approved for use in Australia?
No. As of 2026, retatrutide has not received TGA registration. It is available as a research peptide for qualified laboratory research purposes only — not for human therapeutic use.
Where can I source retatrutide for research in Australia?
Retatrutide (10mg and 20mg per vial, box of 10) is available wholesale from Eternal Peptides Wholesale with available batch-specific Kovera Labs reports. For qualified laboratory research use only.

Key References

Source: Jastreboff AM et al. N Engl J Med. 2023;389(6):514-526. PMID: 37366315

  1. Jastreboff AM et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity. N Engl J Med. 2023;389(6):514-526.
  2. Coskun T et al. LY3437943, a novel triple GIP, GLP-1, and glucagon receptor agonist. Cell Metab. 2022;34(9):1234-1247.
  3. ClinicalTrials.gov. TRIUMPH-1: NCT05882045.
Research Use Disclaimer: All content is derived from published peer-reviewed literature and public clinical trial registries. Products sold by Eternal Peptides Wholesale are for qualified laboratory research use only and are not intended for human therapeutic use or consumption.
Key Takeaways At a Glance
  • ✓Retatrutide (LY3437943) is a synthetic peptide and the first triple GIP/GLP-1/glucagon receptor agonist to enter Phase 3 clinical trials
  • ✓Phase 2 data (Jastreboff et al., NEJM 2023): ~24% body weight reduction at 48 weeks in highest dose cohort — a within-group baseline change, not proof of comparative superiority
  • Retatrutide combines activity at GIP, GLP-1 and glucagon receptors.
  • ✓TRIUMPH-1 Phase 3 results were presented in June 2026; its 80-week primary assessment and 104-week extension are distinct from Phase 2 results
  • ✓Not TGA-approved in Australia as of 2026; available as a research peptide from Eternal Peptides Wholesale for qualified laboratory use only

In This Article

  1. What Is Retatrutide?
  2. Triple Receptor Mechanism
  3. Phase 2 Published Data
  4. Phase 3 TRIUMPH Programme
  5. FAQ

Testing references updated 1 November 2026 for the published Kovera Labs report set. Original research and catalogue snapshot dates remain as stated.

Testing and wholesale procurement: source notes

Product-specific documentation for this guide: RT10: product and report context · RT20: product and report context.

Assess purity separately from peptide quantity. Bachem explains that HPLC purity and net peptide content describe different properties. For a procurement review, start with the published report directory, then match the product, strength and batch to the documents. [1] [2]

Our Kovera Labs reports cover HPLC purity and LC-MS identity, endotoxin (EU/mL), heavy metals (lead, arsenic, cadmium and mercury) and sterility (bacteria and fungi), and each certificate carries its batch number, report ID and a verification link. Results for each tested batch are printed on its product page beside the certificate images. [3] [4] [5]

For wholesale value, compare the same specification and quantity, then check the total payable. The wholesale-price guide explains the method. Products are supplied for laboratory research use only, and TGA requirements apply to research-use supply. [6] [7]

References and bibliography

  1. Bachem. FAQ: analysis of peptides, HPLC purity and net peptide content. Accessed 29 September 2026.
  2. Eternal Peptides Wholesale. Published product-report directory. Accessed 29 September 2026.
  3. Kovera Labs. Sterility testing certificates: results and test conditions. Reports reviewed 1 November 2026; open the individual certificate and its laboratory verification link.
  4. Kovera Labs. Bacterial endotoxin certificates: sample, result, reporting units and limits. Reports reviewed 1 November 2026; open the individual certificate and its laboratory verification link.
  5. Kovera Labs. Heavy-metal certificates: analytes, reporting limits and acceptance criteria. Reports reviewed 1 November 2026; open the individual certificate and its laboratory verification link.
  6. Australian Competition and Consumer Commission. Price displays. Accessed 29 September 2026.
  7. Therapeutic Goods Administration. How we regulate therapeutic peptide products. Accessed 29 September 2026.