What it is
Tirzepatide is a novel dual incretin agonist targeting both GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 receptors. Approved as Mounjaro for type 2 diabetes (2022) and Zepbound for obesity (2023), it has shown unprecedented weight-loss magnitude in clinical trials. Beyond glycemic control and weight loss, it offers cardiovascular benefits by lowering blood pressure and lipid levels.
Mechanism of action
Simultaneous activation of GIP and GLP-1 receptors compounds incretin effects β enhanced insulin secretion, glucagon suppression, delayed gastric emptying, and central appetite reduction. GIP agonism may also improve adipose tissue function and lipid metabolism.
Half-life: ~5 days β weekly dosing.
Evidence summary
SURMOUNT-1 showed 22.5% mean weight reduction at 72 weeks with 15 mg weekly. SURPASS trials demonstrated HbA1c reductions exceeding semaglutide in head-to-head comparison. Newer SUMMIT trial supports use in HFpEF with obesity.
Typical dosing protocols
- Week 1β4: 2.5 mg subcutaneous weekly (initiation)
- Week 5β8: 5 mg weekly
- Increase by 2.5 mg every 4 weeks as tolerated
- Maintenance: 5β15 mg weekly
Side effects & safety
- GI side effects most common during dose escalation
- Hypoglycemia risk increased with insulin/sulfonylurea co-treatment
- Rare: pancreatitis, gallbladder events
- β’ Personal/family history of medullary thyroid carcinoma or MEN2
- β’ Severe gastroparesis
- β’ Pregnancy
Cited studies
- Rosenstock J, Wysham C, FrΓas JP, et al. (2021). Efficacy and safety of a novel dual GIP and GLP-1 receptor agonist tirzepatide in patients with type 2 diabetes (SURPASS-1): a double-blind, randomised, phase 3 trial. The Lancet.PMID 34186022Read source β
- FrΓas JP, Davies MJ, Rosenstock J, et al. (2021). Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes (SURPASS-2). New England Journal of Medicine.PMID 34170647Read source β
- Del Prato S, Kahn SE, Pavo I, et al. (2021). Tirzepatide versus insulin glargine in type 2 diabetes and increased cardiovascular risk (SURPASS-4): a randomised, open-label, parallel-group, multicentre, phase 3 trial. The Lancet.PMID 34672967Read source β
- Jastreboff AM, Aronne LJ, Ahmad NN, et al. (2022). Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). New England Journal of Medicine.PMID 35658024DOI 10.1056/NEJMoa2206038Read source β
- Packer M, Zile MR, Kramer CM, et al. (2025). Tirzepatide for Heart Failure with Preserved Ejection Fraction and Obesity. New England Journal of Medicine.Read source β
All content is for research and educational purposes. Peptides described are sold for laboratory research use only and are not intended to diagnose, treat, cure, or prevent any disease. Always consult a qualified healthcare professional before beginning any protocol.