Overview

Retatrutide is a new entrant into the rapidly-expanding space of anti-obesity peptides. It is known as a GGG tri-agonist. This means that retatrutide works at all of the incretin receptors including GLP-1 and GIP as well as the glucagon receptor itself. Research indicates that retatrutide may be the most effective weight loss peptide yet developed, with some studies showing a rapid and sustained weight loss response as high as 24% of total body weight[1]. Retatrutide is thought to promote weight loss by increasing energy expenditure as well as decreasing energy consumption. It does the former via action at the glucagon receptor and the latter through both central and peripheral appetite control.

Chemical Structure

Sequence: YA1QGTFTSDYSIL2LDKK4AQA1AFIEYLLEGGPSSGAPPPS3
Molecular Formula: C₂₂₁H₃₄₂N₄₆O₆₈
Molecular Weight: 4731.33 g/mol
PubChem SID: 474492335
CAS Number: 2381089-83-2
Synonyms: LY-3437943, NOP2Y096GV

Mechanism of Action

Retatrutide is a triple receptor agonist: one peptide that activates the GLP-1 receptor, the GIP receptor, and the glucagon receptor simultaneously. The first two are shared with tirzepatide and drive glucose-dependent insulin release, slower gastric emptying, and reduced appetite. The glucagon receptor is the addition that sets retatrutide apart. Glucagon-receptor signaling raises energy expenditure — hepatic fat oxidation, lipolysis, and thermogenesis — so the molecule works both sides of the energy-balance equation: it cuts intake through the incretin receptors and lifts output through the glucagon receptor. In preclinical models this triple engagement produced greater weight loss and larger reductions in liver fat than dual or single agonists at matched exposure [2].

Structure and Stability

Like other engineered incretins, retatrutide departs from the native sequence at several positions to resist cleavage by DPP-4 and neprilysin, and carries a lipid acyl chain that binds serum albumin, extending circulation time enough to support once-weekly dosing. The specific substitutions and the acyl group are listed in the structure block above; together they turn a hormone that would otherwise last minutes into a molecule stable enough for weekly subcutaneous administration in studies.

Research Program and Key Findings

Retatrutide is in late-stage clinical development and is not an approved therapeutic, which is why it circulates primarily as a research compound. In the phase 2 obesity trial, once-weekly retatrutide produced dose-dependent weight loss reaching roughly 24% of baseline body weight at 48 weeks on the highest dose — among the largest pharmacologic effects reported for any incretin to date [1]. The same program reported marked reductions in hepatic fat, keeping retatrutide a focus of metabolic-dysfunction-associated steatohepatitis (MASH) research, and a parallel phase 2 effort in type 2 diabetes showed substantial HbA1c lowering. Phase 3 trials are ongoing. For laboratory work the peptide is supplied lyophilized, reconstituted in bacteriostatic water or dilute acetic acid, aliquoted, and stored frozen; it is for in-vitro and analytical research only.

References

[1] Jastreboff AM, et al. Triple-hormone-receptor agonist retatrutide for obesity — a phase 2 trial. N Engl J Med. 2023.
[2] Coskun T, et al. Preclinical characterization of the triple GIP/GLP-1/glucagon receptor agonist LY3437943. Mol Metab. 2022.

Related Product: Retatrutide — for laboratory research use only.