Zepbound's approval label sets the same dose ladder as Mounjaro at a lower list price

The U.S. Food and Drug Administration approved Eli Lilly's Zepbound (tirzepatide) injection for chronic weight management in adults, the company announced on Nov. 8, 2023 ^[1]. It is the same molecule already sold as Mounjaro for type 2 diabetes, now marketed under a different brand name for a different use ^[2]. Lilly set the list price at $1,059.87 a month, which the company says is roughly 20% lower than semaglutide 2.4 mg injection for weight loss ^[1].

The approved label covers adults with obesity (BMI of 30 kg/m² or greater) or adults who are overweight (BMI of 27 kg/m² or greater) and also have a weight-related medical problem such as high blood pressure, dyslipidemia, type 2 diabetes, obstructive sleep apnea or cardiovascular disease ^[1]. It is meant to be used along with a reduced-calorie diet and increased physical activity ^[1]. Zepbound activates both the GIP and GLP-1 hormone receptors, which Lilly says makes it the first and only approved obesity treatment of its kind ^[1].

What the trials showed

Approval was based on the phase 3 SURMOUNT-1 and SURMOUNT-2 trials ^[1]. SURMOUNT-1 enrolled 2,539 adults with obesity, or excess weight plus weight-related medical problems, and did not include people with diabetes ^[1]. At 72 weeks, people on the highest dose (15 mg) lost an average of 48 pounds, and people on the lowest dose studied (5 mg) lost an average of 34 pounds, compared with 7 pounds on placebo ^[1]. Average starting weight was 231 pounds ^[1]. Lilly also reported that 1 in 3 people on the highest dose lost more than 58 pounds — 25% of body weight — versus 1.5% on placebo, though the company notes that figure was not controlled for type 1 error, meaning it is a less statistically rigorous result ^[1].

Doses, price and availability

Zepbound was expected to be available in the U.S. by the end of 2023 in six doses: 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg and 15 mg ^[1]. Lilly said list price does not reflect what most people actually pay once insurance and discounts are applied, and it announced a commercial savings card program ^[1]. People with commercial insurance that covers Zepbound may be eligible to pay as little as $25 for a one-month or three-month prescription; people with commercial insurance that does not cover it may be eligible to pay as little as $550 for a one-month prescription, about 50% below list ^[1]. Terms and conditions apply, and the cards were set to become usable in the days after the drug reached pharmacies ^[1]. Government insurance, including Medicare and Medicaid, was not addressed in the announcement, and the sources do not say how insurers planned to cover the drug.

The label carries a boxed warning about thyroid C-cell tumors, and the drug is contraindicated in people with a personal or family history of medullary thyroid carcinoma, in people with Multiple Endocrine Neoplasia syndrome type 2, and in those with known serious hypersensitivity to tirzepatide or its ingredients ^[1]. It should not be used with other tirzepatide products or any GLP-1 receptor agonist, and it has not been studied in people with a history of pancreatitis or severe gastrointestinal disease, including severe gastroparesis ^[1]. Side effects reported in at least 5% of trial participants included nausea, diarrhea, vomiting, constipation, abdominal pain, indigestion, injection-site reactions, fatigue, hypersensitivity reactions, belching, hair loss and reflux ^[1]. Most nausea, diarrhea and vomiting occurred when doses were increased and generally eased over time, but more people on Zepbound than placebo stopped treatment because of these effects ^[1].

Why it matters for patients

This approval gives U.S. adults a second highly effective injectable option for weight management, in a market where Novo Nordisk had been limiting Wegovy starter doses because of ongoing shortages ^[2]. "In light of increasing rates of both obesity and overweight in the United States, today's approval addresses an unmet medical need," said John Sharretts, who directs the FDA division that oversees obesity drugs ^[2].

The pricing detail matters mainly as a starting point for negotiation between Lilly and insurers and pharmacy benefit managers; what an individual pays depends on coverage, and Lilly itself acknowledged that "far too many hurdles" still block access to obesity treatments ^[1]. Because Zepbound and Mounjaro contain the same molecule, the practical difference for patients is the approved indication and how a plan chooses to cover each brand — not a different drug.

What happens next

Lilly said Zepbound was expected in U.S. pharmacies by the end of 2023 ^[1]. Tirzepatide was also under regulatory review for weight management in Europe, China, the United Kingdom and several other markets at the time of the announcement ^[1].