Zepbound (Tirzepatide)

Zepbound is the brand name for tirzepatide used specifically for chronic weight management, developed by Eli Lilly and approved by the FDA on November 8, 2023. It is a first-in-class dual agonist that activates both the glucose-dependent insulinotropic polypeptide (GIP) receptor and the glucagon-like peptide-1 (GLP-1) receptor simultaneously. This dual mechanism distinguishes tirzepatide from pure GLP-1 agonists: the GIP component enhances insulin sensitivity, may increase energy expenditure through adipose tissue remodeling, and appears to complement the satiety and gastric-slowing effects of GLP-1 activation. The net clinical result is weight loss that consistently surpasses that of semaglutide-based therapies in head-to-head and pivotal trial data. In the 72-week SURMOUNT-1 Phase 3 trial conducted in adults without diabetes, participants taking the highest dose of 15 mg weekly lost an average of 20.9% of body weight — approximately 48 pounds — compared to 3.1% with placebo. At the 10 mg dose, average weight loss was 19.5%. These numbers represented the highest FDA-approved weight-loss drug efficacy ever recorded at the time of approval. A SURMOUNT-2 trial in patients with type 2 diabetes showed weight losses of 12-15%, again well above any comparator. Beyond the scale, Zepbound has amassed an expanding label. In December 2024, it became the first — and to date only — prescription medication approved by the FDA to treat moderate-to-severe obstructive sleep apnea (OSA) in adults with obesity, based on SURMOUNT-OSA trial data showing 25-29 fewer apnea events per hour versus placebo. Zepbound is also under active evaluation for MASH (metabolic dysfunction-associated steatohepatitis), heart failure with preserved ejection fraction, and chronic kidney disease. Administered as a once-weekly subcutaneous injection, Zepbound is available in single-dose autoinjector pens at doses of 2.5, 5, 7.5, 10, 12.5, and 15 mg, with a new monthly KwikPen approved in 2026 that allows four doses to be delivered via a single device — a meaningful convenience upgrade for adherent patients. Self-pay pricing through LillyDirect starts at $299 per month; pharmacy list price is approximately $1,086 for a 28-day supply, with Lilly savings cards bringing cost to as low as $25 per month for eligible commercially insured patients.