The Retatrutide Reference

Retatrutide (developmental code LY3437943, sometimes abbreviated Reta) is a synthetic peptide agonist developed by Eli Lilly. It is a first-in-class once-weekly injectable that engages three hormone receptors simultaneously: glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and glucagon. As of 2026, retatrutide is the only triple receptor agonist of this configuration with published Phase 2 trial data.

A retatrutide peptide pen is not a ballpoint pen, writing implement, or office supply. It is supplied in a pre-filled delivery device at a fixed concentration.

Retatrutide is an investigational compound. It is not approved for therapeutic use in any jurisdiction. The Phase 3 TRIUMPH programme is ongoing across several indications and Eli Lilly has not announced regulatory approval timelines or a UAE commercial launch date.

The molecule was first characterised in published literature by Coskun and colleagues (Cell Metab, 2022;34(9):1234-1247) as a novel triple agonist with balanced glucagon and GLP-1 receptor activity and relatively greater GIP receptor activity. That characterisation underpins the receptor-engagement profile used to interpret all subsequent published trial data.

How retatrutide differs from semaglutide and tirzepatide

Semaglutide engages the GLP-1 receptor only. Tirzepatide engages both GLP-1 and GIP. Retatrutide adds the glucagon receptor as a third pathway in a single molecule. The mechanistic addition of glucagon receptor agonism is what distinguishes retatrutide structurally and pharmacologically within the late-stage incretin class.

Why retatrutide is written as Reta, LY3437943, or triple agonist

Four spelling and naming variants appear across the literature and commercial sources. Each refers to the same compound.

Retatrutide's published research profile is built on three established receptor pathways and the balanced ratio in which the molecule engages them. The pathways are individually well characterised in the broader incretin literature; the contribution of the triple combination is the active research question.

Receptor engagement and pharmacology

The in vitro characterisation by Coskun and colleagues (Cell Metab, 2022;34(9):1234-1247) reports that LY3437943 functions as a peptide agonist at all three receptor targets with balanced glucagon and GLP-1 receptor activity and relatively greater GIP receptor activity. The molecule was selected for clinical development on the basis of this balanced profile and the downstream glycaemic and weight-related endpoints in the discovery programme.

Phase 2 obesity trial findings

Jastreboff and colleagues (N Engl J Med, 2023;389(6):514-526) reported the Phase 2 trial of retatrutide in adults with obesity over a 48-week treatment period. The published data documents receptor-engagement-related effects on body weight across the dose range studied. The publication remains the primary peer-reviewed reference for the obesity research application of retatrutide.

Phase 2 type 2 diabetes trial findings

Rosenstock and colleagues (Lancet, 2023;402(10401):529-544) reported the Phase 2 trial of retatrutide in adults with type 2 diabetes and overweight or obesity. The trial included an active comparator arm (dulaglutide 1.5 mg) and a placebo arm, and characterised the dose-response profile across glycaemic and body weight endpoints over 36 weeks.

Phase 2a metabolic dysfunction-associated steatotic liver disease substudy

Sanyal and colleagues (Nat Med, 2024;30(7):2037-2048) reported a Phase 2a substudy examining liver fat reduction in participants with metabolic dysfunction-associated steatotic liver disease (MASLD) and elevated baseline liver fat. The published findings documented dose-dependent reductions in MRI-PDFF-measured liver fat over the 48-week treatment period, generating research interest in the hepatic application of triple agonism.

All effects described in this section are reported in published clinical trial literature. They are referenced here for research context and do not constitute therapeutic claims or clinical recommendations.

References

The four primary peer-reviewed sources referenced in this guide. The originals are linked in full for anyone who wants the methods behind them.

• 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(9):1234-1247.e9. doi:10.1016/j.cmet.2022.07.013.
• 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(6):514-526. PMID: 37366315. doi:10.1056/NEJMoa2301972.
• 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(10401):529-544. PMID: 37385280. doi:10.1016/S0140-6736(23)01053-X.
• 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(7):2037-2048. doi:10.1038/s41591-024-03018-2.

Retatrutide is currently being studied in Eli Lilly's Phase 3 TRIUMPH programme across several indications. The five principal research application areas listed below are drawn from the published Phase 2 literature and from publicly announced TRIUMPH-programme trial designs. Each represents an active line of investigation, none of which has produced approved clinical interventions as of the date of this guide.

Obesity and overweight research

The principal indication studied in published Phase 2 work. Jastreboff and colleagues (NEJM, 2023) provides the primary obesity research data over a 48-week period. The Phase 3 TRIUMPH-1 trial in adults with obesity reported positive topline results on 21 May 2026 (Eli Lilly press release). Detailed peer-reviewed publication is forthcoming.

Type 2 diabetes research

Rosenstock and colleagues (Lancet, 2023) characterised retatrutide effects on glycaemic control and body weight in participants with type 2 diabetes and overweight or obesity. The trial used dulaglutide as an active comparator. Phase 3 TRIUMPH trials in type 2 diabetes are ongoing.

Metabolic dysfunction-associated steatotic liver disease (MASLD) research

The Phase 2a liver-fat substudy published by Sanyal and colleagues (Nature Medicine, 2024) is the principal source. The hepatic effects observed were disproportionately large relative to body weight changes, prompting active follow-on research into the contribution of glucagon receptor agonism to liver fat reduction.

Obesity-related comorbidity research

The TRIUMPH-4 Phase 3 trial in adults with obesity or overweight and knee osteoarthritis reported positive topline results on 11 December 2025 (Eli Lilly press release). Detailed peer-reviewed publication is forthcoming. Phase 3 trials in obstructive sleep apnoea, cardiovascular and renal outcomes, and chronic low back pain are also part of the programme. Topline figures from these trials are not yet published in peer-reviewed form.

Mechanistic pathway research

Independent of the trial indication, retatrutide serves as a research tool for characterising the contribution of the glucagon receptor pathway within a triple-agonism framework. Researchers studying hepatic metabolism, thermogenic energy expenditure, and incretin signalling use the compound to probe pathway interactions that single- and dual-agonist molecules cannot isolate.

A research peptide pen is a factory-sealed, pre-filled delivery device supplied ready to use at a fixed concentration, with no reconstitution or mixing step at the point of use. The pen format originated in clinical injection devices and has been adapted for research handler use where dose consistency across experiments matters more than per-experiment flexibility.

For retatrutide in the research context, the pen format provides three practical advantages over the lyophilised vial format. Pens arrive ready to use with no reconstitution step. The seal limits airborne contamination during repeated draws. The graduated dose mechanism provides volume consistency that is difficult to match with a manual draw from a stoppered vial.

A pen fixes the concentration set at manufacture, which suits a single-concentration study or a series of replicates at the same dose and reduces handler variance. For in vitro assays that call for a range of working concentrations, researchers derive those from the fixed-concentration stock in the laboratory.

Storage follows a straightforward cold-chain protocol: refrigerated storage at 2 to 8 degrees Celsius before and after first use, with the stability window documented on the Certificate of Analysis. Cold-chain integrity from supplier through delivery is a precondition for any subsequent stability claim.

The Baseline retatrutide peptide pen is supplied at a fixed concentration with batch-specific HPLC purity and mass spectrometry confirmation on the CoA.

The quality of retatrutide is defined by the documentation that accompanies it. A peptide with a published synthesis route but no batch-specific Certificate of Analysis is not a research material; it is an unknown. Researchers procuring retatrutide in the UAE or anywhere else should expect the following at minimum.

• HPLC purity greater than 98 percent, ideally above 99 percent for sensitive research applications.
• Mass spectrometry confirmation of the retatrutide peptide sequence and molecular mass.
• Batch-specific Certificate of Analysis from an independent third-party lab, not just an in-house result.
• Endotoxin testing where the material is intended for cell culture or animal research.
• Documented cold-chain handling from synthesis through shipping, with temperature logs available on request.

For Baseline retatrutide, the per-batch lab report is published at /uae/peptides/retatrutide-32. The CoA documents HPLC purity, mass spectrometry confirmation of the retatrutide sequence, and the in-house concentration assay. Independent third-party reports are available on request.

If there is no CoA, there is no peptide. Only powder.

Retatrutide is an investigational compound that has not received regulatory approval for therapeutic use in any jurisdiction worldwide, including the UAE. Research peptides are not classified as pharmaceuticals under UAE Federal Decree-Law No. 38 of 2024 and retatrutide is not an approved medicine and is only ever considered after a consultation. Your consultant reviews your history first, and you are monitored throughout.

Cold-chain handling matters more in the Gulf than almost anywhere else. Summer ambient temperatures routinely exceed the stability window for these compounds, so where a program is running the chain from storage to delivery is our responsibility rather than a courier’s.

Cold-chain shipping in the GCC requires considered packaging. Ambient temperatures across the summer months routinely exceed 40 degrees Celsius, well above the stability window for research peptides. See the dedicated reference at peptide delivery and GCC cold chain for the operational considerations.

For the full UAE regulatory context covering research peptide procurement, including the relevant law citations and the distinction between research and therapeutic use, see Is it legal to buy peptides in Dubai and the UAE.

Researchers comparing retatrutide to other late-stage incretin compounds will find the side-by-side reference at retatrutide vs tirzepatide vs semaglutide compared useful for contextualising the receptor-engagement profile.

The questions below cover the most common queries from UAE-based researchers and procurement teams. Each answer is independently sourced and can be cross-referenced against the linked product pages and lab results.

Retatrutide is one of several compounds Baseline consultants work with, each documented the same way. The references below provide background on adjacent research compounds frequently studied alongside the late-stage incretin class.

For how this sits against the rest of the range, see the full list of consultation-led treatments in the UAE.