Tirzepatide

Mechanism

In plain terms, tirzepatide imitates two natural gut hormones that lower blood sugar and reduce appetite. Technically, it is a single peptide that agonizes both the glucose-dependent insulinotropic polypeptide (GIP) receptor and the glucagon-like peptide-1 (GLP-1) receptor. This dual incretin action enhances glucose-dependent insulin secretion, suppresses glucagon, slows gastric emptying, and reduces food intake, producing improvements in glycemic control and body weight.

Regulatory Status by Region

• United States (FDA)Approved. Mounjaro for type 2 diabetes (May 2022); Zepbound for chronic weight management (November 2023) and for moderate-to-severe obstructive sleep apnea in adults with obesity (December 2024).
• Australia (TGA)Registered on the ARTG (Mounjaro) for type 2 diabetes and for weight management, available on prescription.
• European Union (EMA)Authorized (Mounjaro) for type 2 diabetes and weight management (marketing authorization granted September 2022).
• WADANot prohibited. Added to the WADA 2026 Monitoring Program, with markers tracked in- and out-of-competition to detect patterns of misuse; not a banned substance.

Key Studies

• Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1; Jastreboff et al.) (N Engl J Med 2022;387:205-216; DOI 10.1056/NEJMoa2206038; PMID 35658024; NCT04184622)
• Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes (SURPASS-2; Frias et al.) (N Engl J Med 2021;385:503-515; DOI 10.1056/NEJMoa2107519; PMID 34170647)
• FDA approves new medication (Zepbound/tirzepatide) for chronic weight management (U.S. Food and Drug Administration press announcement, November 2023)