Tirzepatide
aka Mounjaro · Zepbound
A dual GIP/GLP-1 receptor agonist that produced the largest weight reductions ever recorded for a non-surgical intervention in randomized trials.
Mechanism of action
Simultaneously activates glucose-dependent insulinotropic polypeptide (GIP) and GLP-1 receptors. The GIP arm appears to improve adipose insulin sensitivity and blunt the nausea ceiling that limits GLP-1 monotherapy dosing.
Doses used in published studies
5 mg, 10 mg, and 15 mg once weekly after a 2.5 mg starting dose (SURMOUNT program).
These figures describe what researchers administered under supervision. They are reported for accuracy and are not a protocol, recommendation, or substitute for clinical guidance.
Reported benefits
- 20.9% mean weight loss at 72 weeks on 15 mg (SURMOUNT-1)
- Superior HbA1c reduction versus semaglutide 1 mg (SURPASS-2)
- Reduced progression from prediabetes to type 2 diabetes
- Significant reduction in obstructive sleep apnea events (SURMOUNT-OSA)
Risks & unknowns
- GI intolerance is the dominant adverse-event class
- Hypoglycemia risk when combined with insulin or sulfonylureas
- Weight regain after discontinuation (SURMOUNT-4)
- Long-term data beyond ~3 years remains limited
Legal & regulatory status
FDA-approved for type 2 diabetes (2022) and obesity (2023). Prescription-only in essentially every regulated market.
Check status in your state or country →Key studies
- Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1)
New England Journal of Medicine · 2022
- Tirzepatide versus Semaglutide Once Weekly in Type 2 Diabetes (SURPASS-2)
New England Journal of Medicine · 2021