Zepbound

Overview

Zepbound is Eli Lilly's tirzepatide brand for chronic weight management and obstructive sleep apnea. It is the same molecule as Mounjaro but approved for chronic weight management in adults with a BMI ≥30, or ≥27 with at least one weight-related comorbidity, and for moderate to severe obstructive sleep apnea in adults with obesity. In the SURMOUNT trial program it produced the largest mean weight loss of the drugs scored here.

Mechanism of Action

Identical to Mounjaro — tirzepatide is a dual GIP/GLP-1 receptor agonist. The dual mechanism enhances insulin secretion, suppresses glucagon, slows gastric emptying, and reduces appetite through central and peripheral pathways.

Clinical Evidence

SURMOUNT-1 showed 20.9% mean weight loss at 15 mg over 72 weeks, versus 3.1% on placebo. In SURMOUNT-3, after a 12-week intensive lifestyle intervention, tirzepatide produced an additional 18.4% mean weight loss over 72 weeks, versus a 2.5% gain on placebo. In SUMMIT (731 adults with obesity and heart failure with preserved ejection fraction), tirzepatide lowered the risk of cardiovascular death or worsening heart failure versus placebo (hazard ratio 0.62). SURMOUNT-4 showed that continued tirzepatide treatment prevented weight regain compared to switching to placebo.

Side Effects & Safety

GI side effects (nausea, diarrhea, vomiting, constipation) are the most common, consistent with Mounjaro. The dose-titration schedule is designed to mitigate initial GI intolerance. Zepbound carries the same boxed warning for thyroid C-cell tumors as the other drugs on this page.

FAQ