How does retatrutide work?
Receptor-pharmacology studies characterise retatrutide as an agonist at the GLP-1, GIP and glucagon receptors. Published clinical trials measured body-weight and hepatic fat-fraction endpoints under that pharmacology; those results belong to the studies that produced them.
Retatrutide receptor pathways at a glance
A three-receptor design
Retatrutide is an engineered 39-amino-acid peptide characterised in receptor-pharmacology studies as an agonist at three receptors: GLP-1R, GIPR and GCGR. The triple-receptor profile is referred to in the literature as a "GGG" tri-agonist.
Relative to the dual GLP-1R/GIPR class, the additional arm under investigation is glucagon-receptor agonism. Published work measures hepatic energy-expenditure endpoints associated with that arm alongside the incretin endpoints measured for the class as a whole.
What the published pharmacology shows
Jastreboff et al. (N Engl J Med, 2023; PMID 37385275) published the randomised Phase 2 obesity data: in the 12 mg arm investigators reported a mean change from baseline in body weight of −24.2% at week 48, with more than 90% of that arm reaching a ≥10% reduction. Sanyal et al. (Nat Med, 2024) reported relative hepatic fat-fraction reductions of up to 82.4% in a Phase 2a MASLD population. The Phase 3 TRIUMPH-1 trial (NCT05929066, 2025) reported −28.3% at week 80 in the 12 mg arm, with 45.3% of that arm reaching ≥30%. Published pharmacokinetic work reports hepatic proteolytic metabolism without CYP involvement.
Frequently asked questions
What is retatrutide?
Retatrutide is an investigational triple agonist — it activates the GLP-1, GIP and glucagon receptors — developed by Eli Lilly and still in clinical trials (not approved anywhere). Retatrutide is the research-grade form of this retatrutide peptide, supplied as a lyophilised powder strictly for in-vitro and preclinical laboratory research. It is not an approved medicine.
What receptor systems have been investigated in retatrutide research?
Three: GLP-1R (reported EC50 0.775 nM), GIPR (reported EC50 0.0643 nM, potency reported as 8.9x native GIP) and GCGR (reported EC50 5.79 nM). Receptor coverage is what distinguishes it in the literature from dual (tirzepatide) and single (semaglutide) agonists. These are receptor-pharmacology findings for the molecule, not human-use guidance.
Why is the glucagon receptor investigated alongside GLP-1R?
Glucagon-receptor agonism raises hepatic glucose output in isolation. Published work investigates it in combination with GLP-1R agonism, measuring hepatic energy-expenditure endpoints while monitoring glycaemic endpoints; transient glucose elevation attributable to the GCGR arm was monitored under the study protocols.
Certificates of Analysis for released batches are published on the website. Browse the lab-verified catalogue — research use only.
References
Related research
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