Mechanism of Action
Retatrutide is a next-generation acylated peptide with simultaneous agonist activity at three receptors: GLP-1R, GIP-R, and the glucagon receptor (GcgR). This triple-receptor engagement is mechanistically distinct from dual GLP-1/GIP agonists such as tirzepatide — the addition of glucagon receptor activity provides additive effects on hepatic fat oxidation and energy expenditure in research models.
At GLP-1R, retatrutide stimulates cAMP-PKA signaling in pancreatic β-cells, potentiating glucose-dependent insulin secretion, suppressing glucagon release, and slowing gastric emptying. GIP-R co-agonism contributes to adipocyte lipid metabolism. Glucagon receptor agonism drives hepatic glucose output modulation and upregulates thermogenic gene expression (UCP1, PGC-1α) in brown adipose tissue explant studies.
The extended acyl chain enables albumin binding, accounting for prolonged half-life relative to native GLP-1. Early-phase human trials demonstrated dose-dependent effects on body weight, fasting glucose, triglycerides, and liver fat content.
