What Is Tirzepatide?
Tirzepatide is a first-in-class dual GIP/GLP-1 receptor agonist — meaning it activates two incretin receptors simultaneously. Developed by Eli Lilly, it received FDA approval in 2022 as Mounjaro® for type 2 diabetes and in 2023 as Zepbound® for weight management.
Unlike single-target GLP-1 drugs (semaglutide), tirzepatide's dual mechanism is believed to produce synergistic metabolic effects that neither receptor activation alone can achieve.
How Does It Work?
Tirzepatide binds to both GIP receptors and GLP-1 receptors on cell surfaces, triggering intracellular cAMP signaling cascades. GLP-1 activation stimulates insulin secretion and suppresses glucagon. GIP activation enhances insulin sensitivity and influences energy metabolism and fat storage.
Key Clinical Data
- SURPASS-2 trial: Tirzepatide demonstrated superior A1C reduction vs. semaglutide in head-to-head comparison (Frías et al., 2021, NEJM)
- SURMOUNT-1 trial: Participants receiving 15mg tirzepatide achieved mean weight reduction of 22.5% over 72 weeks (Jastreboff et al., 2022, NEJM)
- Phase 3 trials are ongoing for MASH/NASH, heart failure with preserved ejection fraction, and obstructive sleep apnea
Cited Sources
- According to Frías, J.P. et al. (2021). "Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes." NEJM, 385(6), 503-515. [PubMed]
- According to Jastreboff, A.M. et al. (2022). "Tirzepatide Once Weekly for the Treatment of Obesity." NEJM, 387(3), 205-216. [PubMed]
- According to Rosenstock, J. et al. (2021). "Efficacy and safety of a novel dual GIP and GLP-1 receptor agonist tirzepatide." The Lancet, 398(10295), 143-155. [PubMed]