Retatrutide Research Guide

For laboratory and research use only. Not for human or veterinary use. This page summarizes published scientific literature for educational purposes only.

Retatrutide (research code LY3437943) is the most mechanistically distinctive compound in the GLP-1 family — a first-in-class triple receptor agonist. This guide covers how it works, what the published literature reports, and how it differs from single and dual agonists. It is part of our GLP-1 research peptides hub.

What is retatrutide?

Retatrutide is a synthetic single-molecule agonist that activates three receptors at once: the GLP-1 receptor, the GIP receptor, and the glucagon receptor. It is an investigational compound developed by Eli Lilly and, as of this writing, is being studied in late-stage clinical trials and is not an approved drug. In research terms it represents the “triple agonist” frontier of incretin science.

Mechanism: why three receptors

The literature describes each receptor arm contributing something distinct:

• GLP-1 receptor — glucose-dependent insulin secretion and appetite signaling, the foundation shared with semaglutide.
• GIP receptor — a second incretin pathway, the arm added by dual agonists such as tirzepatide.
• Glucagon receptor — the distinguishing third arm, associated in the literature with increased energy expenditure and reductions in hepatic fat.

What the published literature reports

The Phase 2 trial of retatrutide in obesity was published in the New England Journal of Medicine (Jastreboff et al., 2023) and characterized the triple-agonist profile. Eli Lilly’s Phase 3 TRIUMPH program is studying the investigational drug product across obesity, type 2 diabetes, and related conditions, with readouts reported through 2026. As Lilly states, the investigational molecule is legally available only to participants in its clinical trials. All of this clinical data pertains to the sponsor’s drug product studied in humans — not research-grade material — and is summarized here only to explain the science. Consult primary sources on PubMed.

Dosing used in the clinical trials

The following reports the dose regimens administered in published clinical trials of the investigational retatrutide drug product, for scientific context only. It is not a recommendation, a protocol, or guidance for use, and it does not describe how the research-grade material sold here should be used. Self-administering research peptides can be dangerous; these products are strictly for laboratory research.

In the Phase 2 obesity trial (Jastreboff et al., New England Journal of Medicine, 2023), retatrutide was given once weekly by subcutaneous injection, with participants randomized to one of four target maintenance doses reached through gradual escalation. The Phase 3 TRIUMPH program studied 4, 9, and 12 mg maintenance doses.

At the highest dose (12 mg), the Phase 2 trial reported a mean body-weight reduction of about 24.2% at 48 weeks; Phase 3 TRIUMPH-1 reported about 28.3% at 80 weeks. Retatrutide is investigational and not approved — per its developer, it is legally available only to participants in its clinical trials. Sources: NEJM 2023; Lilly TRIUMPH program.

Laboratory handling

Research-grade retatrutide ships lyophilized and is characterized by HPLC, with a Certificate of Analysis on our Lab Results page. It is reconstituted with sterile bacteriostatic water; use the reconstitution calculator for the exact diluent volume and the reconstitution guide for the full procedure. Browse research-grade options in our GLP-1 catalog; bacteriostatic water is included free with every order.

Frequently asked questions

What makes retatrutide a “triple agonist”?

It activates the GLP-1, GIP, and glucagon receptors with a single molecule, whereas semaglutide engages one receptor and tirzepatide engages two.

Is retatrutide an approved drug?

No. It is investigational and, per its developer, is being evaluated in clinical trials. Research-grade material is supplied strictly for laboratory use.

What is the glucagon arm for?

In the published literature, glucagon-receptor activation is associated with increased energy expenditure and reduced hepatic fat — the feature that distinguishes triple agonists from dual agonists.

Disclaimer: Research-grade retatrutide supplied by MyGLP1Store is strictly for laboratory and in-vitro research. It is not an approved drug, not a supplement, and not for human or veterinary use. Clinical trial data above pertains to the investigational drug product studied by its sponsor.