Retatrutide
An investigational triple agonist of GLP-1, GIP, and glucagon receptors studied for effects on weight regulation and metabolic health.
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What is Retatrutide?
Retatrutide is an investigational synthetic peptide engineered by Eli Lilly to simultaneously activate three distinct receptors involved in metabolic regulation: the glucagon-like peptide-1 (GLP-1) receptor, the glucose-dependent insulinotropic polypeptide (GIP) receptor, and the glucagon receptor. It represents a further step in the evolution of incretin-based research compounds, building on the success of selective GLP-1 agonists and dual GIP/GLP-1 agonists. The peptide is 39 amino acids in length with structural features that confer balanced activity at all three target receptors and an attached fatty acid moiety that enables albumin binding for once-weekly dosing.
Retatrutide is notable in research for the magnitude of effects observed in Phase 2 trials, with published data showing some of the largest weight reductions documented with any pharmacological intervention. The compound remains investigational and is the subject of the Phase 3 TRIUMPH clinical trial program examining effects across obesity, type 2 diabetes, obstructive sleep apnea, knee osteoarthritis, and metabolic dysfunction-associated steatohepatitis (MASH). It has not received regulatory approval in any jurisdiction.
Mechanism of action
Retatrutide’s mechanisms of action have been investigated across multiple pathways:
- GLP-1 receptor agonism: Activation stimulates glucose-dependent insulin secretion, suppresses inappropriate glucagon release, delays gastric emptying, and engages central appetite-regulating circuits.
- GIP receptor agonism: Research suggests GIP receptor activation enhances insulin secretion synergistically with GLP-1 and influences adipose tissue function, lipid metabolism, and potentially energy expenditure.
- Glucagon receptor agonism (partial): The most novel component, partial glucagon receptor activation increases energy expenditure, promotes hepatic lipolysis and fat oxidation, and reduces hepatic steatosis in research models.
- Balanced multi-receptor design: The peptide’s structure balances glucagon receptor activity (which alone would raise glucose) against the more potent insulinotropic effects of GLP-1 and GIP activation, with the net effect favoring glycemic improvement in studies.
- Albumin-mediated half-life extension: A fatty acid conjugation enables reversible albumin binding, dramatically extending plasma residence time and supporting once-weekly subcutaneous dosing in research protocols.
- Effects on hepatic fat and metabolism: Studies have documented substantial reductions in hepatic fat content and improvements in cardiometabolic markers exceeding those seen with selective GLP-1 or dual GIP/GLP-1 agonism.
These pathways are characterized in both preclinical models and Phase 2 human research.
Research applications
Retatrutide has been investigated across several research domains, with the most active areas including:
- Obesity research (Phase 2 and Phase 3): The Phase 2 obesity trial documented mean weight reductions of approximately 24% at 48 weeks at the highest tested dose, with weight loss appearing to still be ongoing at trial end. The Phase 3 TRIUMPH-1 trial is examining chronic weight management.
- Type 2 diabetes research: A Phase 2 trial in type 2 diabetes demonstrated HbA1c reductions of approximately 2 percentage points and substantial weight loss, with TRIUMPH-2 examining outcomes in larger Phase 3 populations.
- Hepatic and MASH research: Sub-studies have shown substantial reductions in hepatic fat content, with some participants achieving near-complete resolution of hepatic steatosis. Phase 3 investigation in MASH/NASH populations is ongoing.
- Cardiovascular outcomes: The TRIUMPH-3 cardiovascular outcomes trial is examining effects on major adverse cardiovascular events in populations with obesity and elevated cardiovascular risk.
- Other research areas: Active investigation includes obstructive sleep apnea, knee osteoarthritis, and applications in specific patient populations.
This compound is intended for laboratory research use only. It has not been approved for human therapeutic use by any regulatory agency.
Storage & reconstitution
In its lyophilized form, retatrutide tolerates ambient temperatures during shipping but should be stored long-term at -20°C, protected from light. Properly stored lyophilized peptide remains stable for 24 months or longer.
Once reconstituted with bacteriostatic water for injection, retatrutide solutions should be stored refrigerated at 2-8°C and used within 28 days. Avoid repeated freeze-thaw cycles, which can degrade peptide structure and reduce activity.
Visual inspection should be performed before each use. The reconstituted solution should be clear and colorless. Reject any solution that appears cloudy, discolored, or contains visible particulate matter.
For step-by-step reconstitution calculations, see our reconstitution calculator.
For laboratory research use only. The compound described on this page is intended exclusively for in vitro research and laboratory experimentation by qualified researchers and is not for human or veterinary use. It is not a drug, food, dietary supplement, or cosmetic, and has not been approved by the FDA, Health Canada, EMA, or any other regulatory authority for the diagnosis, treatment, cure, mitigation, or prevention of any disease or medical condition. The information provided on this page is for educational and reference purposes only and does not constitute medical advice. By accessing this content you confirm that you are a qualified researcher purchasing for legitimate laboratory purposes.