Retatrutide is a once-weekly triple GLP-1/GIP/glucagon receptor agonist — Phase 2 data showed 24.2% mean body weight reduction at 48 weeks, the highest result in obesity pharmacology Phase 2 trial history at publication.
Product definition
What is Retatrutide?
Retatrutide is a once-weekly triple GLP-1/GIP/glucagon receptor agonist — Phase 2 data showed 24.2% mean body weight reduction at 48 weeks, the highest result in obesity pharmacology Phase 2 trial history at publication.
Retatrutide (LY3437943; Eli Lilly) is a 39-amino-acid acylated peptide engineered for balanced tri-agonism at GLP-1R, GIPR, and the glucagon receptor (GcgR). Like tirzepatide, it uses a non-native peptide backbone and a fatty acid conjugate for albumin binding (~6-day half-life, once-weekly dosing). Unlike tirzepatide, the glucagon receptor agonism adds a third pharmacological dimension: glucagon receptor activation promotes hepatic glucose mobilization, enhances adipose tissue lipolysis, and drives thermogenesis in brown adipose tissue.
The TRIUMPH Phase 2 trial (2023, NEJM) was the pivotal publication: dose-escalating retatrutide 12 mg weekly produced 24.2% weight reduction at 48 weeks in adults with obesity, a result that exceeded tirzepatide's 22.5% SURMOUNT-1 result at 72 weeks when normalized for trial duration. Phase 3 TRIUMPH trials are ongoing, making retatrutide the most advanced triple agonist in the clinical obesity pharmacology pipeline.
Research context
How is Retatrutide described in the research literature?
Retatrutide activates GLP-1 receptors (satiety, gastric emptying), GIP receptors (adipose lipid handling, beta cell protection), and glucagon receptors (hepatic glucose regulation, thermogenic energy expenditure via brown adipose activation) simultaneously. Phase 2 results document 24.2% body weight reduction at 48 weeks with 12 mg weekly dosing — exceeding prior dual-agonist Phase 2 benchmarks.
Compound profile
Key facts about Retatrutide
- Class
- Triple GLP-1/GIP/glucagon receptor agonist
- Developer
- Eli Lilly (LY3437943)
- Molecular weight
- ~4,997 Da
- Half-life
- ~6 days (albumin-bound in vivo)
- Phase 2 result
- 24.2% mean body weight reduction at 48 weeks (12 mg weekly)
- Clinical status
- Phase 3 TRIUMPH trials ongoing
- Research category
- Triple incretin pharmacology, obesity, thermogenesis, glucagon biology
- Storage
- Lyophilized: −20°C. Reconstituted: 2–8°C, use within 30 days
Research areas
What research areas is Retatrutide associated with?
- Triple GLP-1/GIP/glucagon receptor agonism — pharmacologically distinct from dual GLP-1/GIP agonists
- Phase 2 TRIUMPH: 24.2% mean body weight reduction at 48 weeks — highest Phase 2 obesity pharmacology result at publication
- Glucagon receptor activation contributes thermogenic energy expenditure dimension absent from dual agonists
- ~6-day half-life enables once-weekly dosing protocols in research models
- Reference compound for glucagon receptor contribution studies alongside GLP-1R and GIPR pharmacology
- Most advanced triagonist in clinical pipeline — TRIUMPH Phase 3 ongoing, robust preclinical dataset
Research audience
Who researches Retatrutide?
Retatrutide is used by researchers studying triagonist incretin pharmacology, glucagon receptor biology, thermogenesis and energy expenditure mechanisms, adipose tissue lipid handling, and the pharmacological ceiling of multi-receptor metabolic interventions.
Preclinical research overview
What does the preclinical literature say about Retatrutide?
Retatrutide was developed by Eli Lilly following the commercial and clinical success of tirzepatide, with the hypothesis that adding glucagon receptor agonism to GIP/GLP-1 co-activation would further amplify metabolic outcomes. The glucagon receptor has a complex role in metabolic biology: historically studied as a counter-regulatory hormone that raises blood glucose, its role in energy expenditure and adipose thermogenesis has become a research priority in the context of obesity pharmacology.
The TRIUMPH Phase 2 trial confirmed the hypothesis: the triple agonism approach produced weight reduction that exceeded dual agonism at equivalent trial timepoints, suggesting the glucagon receptor contribution to energy expenditure is pharmacologically meaningful in the context of combined incretin receptor engagement.
The research mechanistic questions driving current investigation include: (1) whether the glucagon component primarily contributes through thermogenesis in BAT, through hepatic lipid metabolism changes, or through both; (2) whether the glucagon receptor activity produces any glycemic liability that must be managed by the simultaneous GLP-1R insulinotropic action; and (3) how the three receptor pathways interact at the level of downstream signaling (cAMP) in cells that co-express multiple receptors.
Common questions
Frequently asked about Retatrutide
What does the glucagon receptor add that tirzepatide lacks?
Tirzepatide's dual GIP/GLP-1 agonism primarily addresses satiety, gastric emptying, insulin secretion, and adipose lipid handling. Glucagon receptor activation in retatrutide adds hepatic glycogenolysis regulation, lipolysis amplification, and thermogenic activation of brown adipose tissue — an energy expenditure dimension separate from the satiety-driven caloric restriction of GLP-1R/GIPR effects. The Phase 2 body weight reduction differential suggests this additional mechanism contributes meaningfully to total metabolic outcomes.
Does the glucagon component cause hyperglycemia?
In the context of simultaneous GLP-1R agonism (which stimulates insulin release), the glucagon receptor's glycemic effects appear to be counterbalanced. Phase 2 TRIUMPH data showed mean HbA1c reductions in both diabetic and non-diabetic participants — suggesting the glucagon-induced hepatic glucose output is pharmacologically managed by the co-engaged GLP-1R insulinotropic axis. This glycemic management is a key pharmacological feature of the triagonist design.
Is retatrutide approved? What is its current status?
Retatrutide is not yet approved. Phase 2 TRIUMPH data was published in 2023 (NEJM). Phase 3 TRIUMPH trials are ongoing as of this writing. The compound is available as a research reference compound — for investigators studying triagonist pharmacology in preclinical models or requiring reference standard material for comparative research.
Research Use Only
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