On Nov. 8, 2023, the Food and Drug Administration (FDA) approved Eli Lilly’s Zepbound^™ (tirzepatide) injection. It is indicated for weight loss and management in adults who are obese (who have a body mass index [BMI] of at least 30 kg/m²) or who are overweight (a BMI of 27 kg/m² or higher) and who have weight-related medical conditions. Tirzepatide is both a glucose-dependent insulinotropic polypeptide (GIP) and a glucagon-like peptide-1 (GLP-1) hormone receptor agonist and is the same active ingredient found in the company’s Mounjaro^®, which was approved last year for treating type 2 diabetes. Starting at 2.5mg/week as a subcutaneous (SC) injection, the recommended dose then doubles to 5mg/week after one month. If further increases are needed, doses may be increased by 2.5mg/week at intervals of no less than one month. The maximum recommended dose is 15mg per week. Zepbound is expected to be available before the end of 2023 with a cost of around $1,060 per month. For full prescribing information see here. 

At a Glance

• Brand (Generic) Name: Zepbound (tirzepatide)
• Manufacturer: Eli Lilly
• Date Approved: Nov. 8, 2023
• Indication: in addition to a reduced-calorie diet and increased physical activity for chronic weight management in adult patients who have an initial BMI of 30 kg/m² or greater or 27 kg/m² or greater in the presence of at least one weight-related comorbid condition such as hypertension, dyslipidemia, type 2 diabetes, obstructive sleep apnea or cardiovascular disease
• Dosage Forms Available: single-dose pens containing 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg or 15mg per 0.5mL of Zepbound for SC injection
• Launch Date: By the end of 2023
• Estimated Annual Cost: About $12,720 per year for the average list price
• Tirzepatide is both a glucose-dependent insulinotropic polypeptide (GIP) and a glucagon-like peptide-1 (GLP-1) hormone receptor agonist. It is the same active ingredient found in the company’s Mounjaro^®, which was approved in May 2022 for treating type 2 diabetes.
• The obesity epidemic continues to grow in the U.S. Current estimates are that 42.5% of U.S. adults age 20 years and older were obese in 2018 and 31.1% more were overweight, with no significant difference seen between genders.
• Obesity is a risk factor for many conditions, including diabetes, high cholesterol, and high blood pressure. When sustained, just a moderate weight loss of 5% to 10% of the starting weight can result in a significant reduction in obesity-related conditions.
• Guidelines recommend assessing patient readiness to make lifestyle changes to accomplish weight loss, and determine goals and comprehensive lifestyle intervention strategies with a goal of achieving 5% to 10% weight loss and adequate improvement in any health targets.
• In one of its pivotal trials, SURMOUNT-1, patients taking Zepbound along with a reduced caloric meal plan and increasing physical activity saw a weight loss of 22.5% when taking the highest dose (15mg per week) of the drug versus 2.4% in the control group after 72 weeks.
• As with other GLP-1 agonists and Mounjaro, the labeling for Zepbound contains a boxed warning about tumors of the thyroid gland (thyroid C-cell tumors) that have occurred among laboratory rodents treated with some GLP-1 receptor agonists in preclinical studies. However, whether the drugs cause humans to develop thyroid C-cell tumors, such as medullary thyroid carcinoma (MTC), is not yet known. Patients who have MTC, individuals with close family members who have thyroid C-cell tumors, and patients who have Multiple Endocrine Neoplasia syndrome type 2 (tumors in more than one gland) should not use any drug in the class.
• Other prescription drugs marketed in the U.S. for weight loss and management include Novo Nordisk’s injectable products Saxenda^® (liraglutide) and Wegovy^® (semaglutide), and the oral drugs, Contrave^® (bupropion/naltrexone – Currax Pharmaceuticals) extended-release tablets, Qsymia^® (phentermine/topiramate – Vivus) extended-release capsules and Xenical^® (orlistat – Cheplapharm/H² Pharma) capsules. Phentermine (generics) tablets and capsules also are available, but just for short-term use. Additionally, a lower-strength form of orlistat, alli^® (GlaxoSmithKline), is sold over-the-counter (OTC).
• Eli Lilly used a Priority Review Voucher to reduce FDA review time for Zepbound.