What Is Tirzepatide?

Overview

Tirzepatide (LY3298176) is a 39-amino-acid synthetic peptide engineered as a dual agonist of the GIP and GLP-1 receptors - the two principal incretin receptors. The peptide backbone is derived from the native GIP sequence and includes two 2-aminoisobutyric acid (Aib) residues that confer resistance to DPP-IV degradation, together with a C20 fatty-diacid chain attached at Lys20 that promotes reversible albumin binding and a circulating half-life of roughly five days.[1][4]

Native GIP and GLP-1 are incretin hormones released from intestinal K-cells and L-cells respectively in response to nutrient intake, and both potentiate glucose-dependent insulin secretion from pancreatic beta-cells. Tirzepatide is studied as a single molecule that engages both pathways simultaneously, allowing investigators to probe the combined and interacting effects of GIP-receptor and GLP-1-receptor signaling on insulin secretion, glucagon dynamics, and energy-balance endpoints.[2][7]

Discovery and design rationale

Tirzepatide was reported by Coskun and colleagues at Eli Lilly as the first unimolecular dual GIP/GLP-1 receptor agonist to reach clinical proof of concept. The design objective was to combine GIP-receptor and GLP-1-receptor agonism in a single fatty-acylated peptide, testing the hypothesis that balanced co-agonism produces greater metabolic effects than GLP-1-receptor agonism alone.[1]

Research framework

Within the incretin research-peptide family, tirzepatide is most directly compared with selective GLP-1-receptor agonists such as semaglutide and with the triple GIP/GLP-1/glucagon agonist retatrutide. Tirzepatide is the dual-agonist reference compound in this set, giving investigators a tool to isolate the contribution of added GIP-receptor engagement relative to GLP-1-only agonism.[5][6]