In-depth entry

Tirzepatide

also known as: Mounjaro, Zepbound, LY3298176

A once-weekly GLP-1/GIP dual agonist that produced unprecedented weight loss in SURMOUNT trials — up to ~21% at highest dose.

A 39-amino-acid synthetic peptide with balanced agonism at GIP and GLP-1 receptors, engineered for a ~5-day half-life via C20 fatty acid conjugation.

Mechanism of action

Dual agonist at GIP and GLP-1 receptors. GLP-1 effects include enhanced insulin secretion, reduced glucagon, slowed gastric emptying, and central appetite suppression. GIP contribution is still being characterized but appears to enhance the metabolic effects and may improve GI tolerability compared with GLP-1 monoagonism. Produced greater weight loss than semaglutide in head-to-head SURPASS-2 and SURMOUNT-5 trials.

Primary uses

Type 2 diabetes mellitus
Chronic weight management (BMI ≥30, or ≥27 with comorbidity)
Obstructive sleep apnea (Zepbound expanded indication, December 2024)

Typical dosing

2.5–15 mg weekly (subcutaneous)

Titrated over 20+ weeks. Maximum dose 15 mg weekly. Maintenance typically 10 or 15 mg.

Regulatory status

FDA-approved as Mounjaro (T2DM, May 2022) and Zepbound (chronic weight management, November 2023). Manufactured by Eli Lilly.

References

[fda-pi] Mounjaro (tirzepatide) Prescribing Information. Eli Lilly.
[fda-pi] Zepbound (tirzepatide) Prescribing Information. Eli Lilly.
[clinical-trial] Jastreboff AM, et al. "Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1)." N Engl J Med, 2022;387:205-216.
[clinical-trial] Aronne LJ, et al. "Tirzepatide vs Semaglutide for Obesity (SURMOUNT-5)." N Engl J Med, 2025.

Related peptides

Semaglutide

A once-weekly GLP-1 receptor agonist FDA-approved for type 2 diabetes and chronic weight management.

Retatrutide

An investigational triple hormone agonist that produced ~24% weight loss at 48 weeks in Phase 2 — the largest in any single-agent obesity trial to date.

Liraglutide

The first once-daily GLP-1 analog to be FDA-approved for both type 2 diabetes (Victoza) and chronic weight management (Saxenda).

Disclaimer

This entry is for educational purposes only and does not constitute medical advice. Dosing information reflects published regulatory or research data and is not a recommendation. Many compounds described here are not approved for human use in the United States. Consult a licensed medical professional before considering any peptide therapy.