Retatrutide

Triple GIP/GLP-1/glucagon receptor agonist; targets three pathways for synergistic fat reduction

Retatrutide (LY3437943) is an investigational triple hormone receptor agonist that simultaneously activates GLP-1, GIP (glucose-dependent insulinotropic polypeptide), and glucagon receptors, combining the complementary metabolic actions of all three incretin and counterregulatory hormone pathways in a single weekly injection. The GLP-1 component drives satiety and insulin secretion, GIP enhances adipose lipid metabolism and further modulates appetite, and glucagon receptor activation increases energy expenditure — together producing greater weight loss than single or dual agonists in the same receptor class. A Phase 2 randomized controlled trial published in the New England Journal of Medicine demonstrated dose-dependent weight reductions of up to 24% of body weight at 48 weeks, among the largest reported for any pharmacological obesity treatment. Retatrutide has not received FDA approval; it is under Phase 3 registrational evaluation (TRIUMPH trials) as of 2025 for obesity, obstructive sleep apnea, and knee osteoarthritis. Retatrutide cost and access As of mid-2026, retatrutide has not received FDA approval and is not commercially available as a branded pharmaceutical. It is in late-stage (Phase 3) clinical development through Eli Lilly. Access pathways include: enrollment in active clinical trials (listed on ClinicalTrials.gov), research-use peptide vendors who supply retatrutide for laboratory/research contexts (not for human use), and a limited number of compounding pharmacies that compound investigational or pre-approval compounds under provider-supervised protocols. Cost per month of research-grade retatrutide from vendors varies considerably by quantity and formulation. Branded pharmaceutical pricing will be established at approval; given tirzepatide's pricing trajectory and the triple-agonist mechanism, analyst forecasts suggest a premium pricing position relative to existing GLP-1 agonists. Retatrutide vs survodutide: Survodutide (BI 456906, Boehringer Ingelheim + Zealand Pharma) is a dual GLP-1 and glucagon receptor agonist in Phase 3 development for MASH (metabolic dysfunction-associated steatohepatitis) and obesity. Compared to retatrutide, survodutide lacks the GIP receptor component; retatrutide's triple agonism adds GIP-mediated adipose lipid oxidation to the GLP-1 + glucagon combination. In trial comparisons, both compounds show substantial weight reductions (retatrutide 24.2% at 12mg/week in Phase 2; survodutide 18.7% at highest dose in Phase 2). Neither compound has a direct head-to-head trial yet. Both represent the next tier beyond tirzepatide in the GLP-1 + additional agonism category. Retatrutide's MASH indication (liver fat reduction) also overlaps with survodutide's primary development focus. The competitive landscape in this category is evolving rapidly as multiple Phase 3 readouts are expected through 2026–2027.