Tirzepatide is a long-acting injectable dual GIP and GLP-1 receptor agonist, the active ingredient of Eli Lilly's Mounjaro and Zepbound. It is the first-in-class "twincretin": a single molecule that activates two incretin receptors at once (lab code LY3298176).
Effect on Hunger and Weight
Tirzepatide combines the action of two satiety hormones. Through the GLP-1 receptor it acts on the brain's hunger centres, blunting appetite and food cravings, while through the GIP receptor it further amplifies this effect and improves insulin sensitivity. It also slows gastric emptying, so fullness comes sooner and lasts longer. In a head-to-head trial (SURPASS-2) tirzepatide outperformed semaglutide for weight loss, and in the SURMOUNT programme weight loss reached around 20% or more — the highest figure among available incretin drugs.
Blood Sugar Control
Both receptors enhance glucose-dependent insulin secretion and suppress glucagon, so tirzepatide markedly lowers glucose and HbA1c with a low risk of hypoglycaemia. GIP receptor activation additionally improves tissue insulin sensitivity.
Duration of Action
A C20 fatty (eicosanedioic) acid on lysine-20, attached via a linker, binds tightly to blood albumin, extending the half-life to about 5 days — hence once-weekly subcutaneous dosing. Resistance to the DPP-4 enzyme is provided by two α-aminoisobutyric acid (Aib) substitutions at positions 2 and 13.
Properties
A 39-amino-acid modified peptide based on the GIP sequence. Formula C₂₂₅H₃₄₈N₄₈O₆₈, molecular weight 4813.53 Da. CAS 2023788-19-2, PubChem CID 163285897. 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