Retatrutide

Retatrutide, listed in the literature under the development code LY3437943, stands for the third generation of incretin research: after mono and dual agonists, a third receptor joins the set.

The three targets:

• GLP-1 receptor: the classical incretin pathway.
• GIP receptor: here retatrutide is about nine times more potent than the endogenous ligands.
• Glucagon receptor: its activation is linked in research to higher energy expenditure and stronger lipid breakdown.

Numbers from the trials:

• Phase 2: up to 24.2 percent less body weight after 48 weeks in obese participants, which ranks it among the most potent molecules of its class.
• Liver: in research on MASLD, short for metabolic dysfunction-associated steatotic liver disease, hepatic fat dropped by more than 80 percent.
• Phase 3: the TRIUMPH program is currently producing further data.

On structure: retatrutide is a single protein coupled to a fatty acid chain. That chain stretches the residence time to a half-life of about six days, so the trials dosed subcutaneously once a week. Because potency is high according to the studies, protocols there managed with comparatively low dose windows. The sources below give you the phase 2 trial, the liver data, a review and a meta-analysis.

As a triple agonist, retatrutide shows an overall acceptable tolerability profile in the studies, but one that is clearly dose-dependent in the phase 2 data and dominated by gut effects.

• Stomach and bowel: nausea, vomiting, diarrhea and constipation are documented most often, with a clear link to how fast the dose was raised; slow titration brought the rate down.
• Fluids: the strongly blunted appetite lowers food and fluid intake in the trials, and the literature flags a higher dehydration risk.
• Pulse: the glucagon component is associated in the literature with mild increases in heart rate, which gets attention given the high potency.
• Muscle and gallbladder: part of the weight lost is muscle mass, and gallbladder complaints are described during rapid weight loss.
• Time horizon: the molecule is young; solid human data over long periods do not exist yet.

This summary is no substitute for medical advice.

• Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial - the phase 2 trial behind the 48-week figures.
• Triple hormone receptor agonist retatrutide for MASLD - the phase 2a work on liver fat.
• Retatrutide - A Game Changer in Obesity Pharmacotherapy - a 2025 review of the molecule's pharmacology.
• Efficacy and safety of retatrutide - systematic review and meta-analysis - combines the randomized trials available to date.