Retatrutide is a long-acting injectable triple agonist of the GLP-1, GIP and glucagon (GCGR) receptors, developed by Eli Lilly (lab code LY3437943). It is a "triagonist": a single molecule that activates three metabolic receptors at once. The drug is currently in clinical development and is not yet approved by regulators.
Effect on Hunger and Weight
Retatrutide combines three weight-control mechanisms. Through the GLP-1 receptor it blunts appetite and food cravings and slows gastric emptying; through the GIP receptor it amplifies this effect and improves insulin sensitivity; and the added glucagon receptor raises energy expenditure and increases the use of fat as fuel. It is this third, glucagon component that sets retatrutide apart from dual (tirzepatide) and pure GLP-1 (semaglutide) agonists. In phase 2, dose-dependent weight loss in people with obesity reached about 24% at 48 weeks — the highest figure among incretin compounds in development.
Blood Sugar Control
Retatrutide enhances glucose-dependent insulin secretion and suppresses pancreatic glucagon, lowering fasting and post-meal glucose with a low risk of hypoglycaemia.
Duration of Action
A lipid modification (C20 fatty acid) enables binding to blood albumin and a half-life of about 150–180 hours (6–7 days), allowing once-weekly subcutaneous dosing. α-Aminoisobutyric acid (Aib) substitutions make the peptide resistant to enzymatic degradation.
Properties
A synthetic 39-amino-acid peptide based on the GIP sequence. Formula C₂₂₁H₃₄₂N₄₆O₆₈, molecular weight 4731.33 Da. CAS 2381089-83-2, PubChem CID 171390338. White lyophilized powder for reconstitution.
Storage
Store at 2–8°C protected from light; it briefly tolerates room temperature during shipping. After reconstitution keep refrigerated, do not freeze, and use within a few weeks.
BIOLABCHEMICALS