Retatrutide (LY3437943) is an experimental triple-hormone receptor agonist developed by Eli Lilly and Company for the treatment of obesity, type 2 diabetes, and metabolic dysfunction-associated steatotic liver disease (MASLD). It simultaneously activates the glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and glucagon receptors, giving it a unique "triple attack" mechanism that regulates appetite, slows gastric emptying, improves glycemic control, and increases energy expenditure.
In a phase 2 clinical trial, participants with obesity (without diabetes) achieved up to 24.2% mean weight loss after 48 weeks at the highest dose (12 mg), significantly outperforming existing GLP-1 and dual agonist drugs like semaglutide (Wegovy) and tirzepatide (Mounjaro). It is administered via once-weekly subcutaneous injection, with a half-life of approximately 6 days.
Retatrutide is currently in phase 3 clinical trials (e.g., the TRIUMPH program) and is not yet approved by the FDA. Due to its anticipated efficacy, it has been dubbed the "King Kong" of weight-loss drugs.