Retatrutide: What We Know From Phase 2 Trials

What is Retatrutide?\n\nRetatrutide (LY3437943) is a novel triple-agonist peptide developed by Eli Lilly targeting three receptors simultaneously:\n\n1. GIP receptor (Glucose-dependent insulinotropic polypeptide)\n2. GLP-1 receptor (Glucagon-like peptide-1)\n3. Glucagon receptor\n\n## Phase 2 Trial Results\n\nThe Phase 2 trial (published in NEJM, 2023) enrolled 338 participants with obesity.\n\n### Key Findings\n\n- 24-week results: Up to 17.5% body weight loss\n- 48-week results: Up to 24.2% body weight loss at the 12mg dose\n- Dose-dependent: Higher doses showed greater efficacy\n\n### Dosing Groups\n\n| Dose | 24-Week Loss | 48-Week Loss |\n|------|-------------|-------------|\n| 1mg | -7.2% | -8.7% |\n| 4mg | -12.9% | -17.1% |\n| 8mg | -14.5% | -22.8% |\n| 12mg | -17.5% | -24.2% |\n\n## How It Compares\n\n- Semaglutide (Wegovy): ~15% at 68 weeks\n- Tirzepatide (Mounjaro): ~22.5% at 72 weeks\n- Retatrutide: ~24.2% at just 48 weeks\n\n## Mechanism Advantage\n\nThe triple-agonist approach may explain the superior results:\n\n- GLP-1: Appetite suppression and insulin sensitization\n- GIP: Enhanced incretin effect and fat metabolism\n- Glucagon: Increased energy expenditure and hepatic fat reduction\n\n## Side Effects\n\nMost common adverse events were GI-related:\n- Nausea (most common, typically transient)\n- Diarrhea\n- Vomiting\n- Constipation\n\n## Current Status\n\nRetatrutide is currently in Phase 3 clinical trials. FDA approval is not expected before 2026-2027.\n\n## What This Means for Research\n\nThe triple-agonist approach represents a new frontier in metabolic peptide research, potentially offering superior efficacy compared to dual-agonists like tirzepatide.