The recent decision by the Food and Drug Administration (FDA) to greenlight the weight loss drug tirzepatide has introduced a robust addition to the rapidly expanding array of obesity medications. The drug, set to be marketed under the name Zepbound, shares its active compound with the diabetes medication Mounjaro, which has been utilized off-label for weight loss since its initial approval in May 2022. This FDA approval may pave the way for broader insurance coverage and increased prescriptions.
Zepbound represents the second drug in a novel class of obesity medications sanctioned for weight loss, following Wegovy. According to Dr. Scott Hagan, an assistant professor of medicine at the University of Washington, Zepbound is likely the most effective treatment for obesity, rivaling bariatric surgery. However, the availability of Mounjaro, which shares the same compound, has been limited since its market introduction in the previous year.
Dr. Andrew Kraftson, a clinical associate professor at Michigan Medicine, likened the situation to the demand surge witnessed with another medication, Ozempic. He anticipates a similar clamor for Zepbound among patients due to the heightened interest in weight loss medications.
The FDA has specified that Zepbound is approved for individuals with a body mass index (BMI) of 30 or higher, categorizing them as having obesity. Alternatively, individuals with a BMI of 27 or more, coupled with certain weight-related conditions like high blood pressure, are also eligible. Regulators recommend using the drug in conjunction with a reduced-calorie diet and increased physical activity.
Manufactured by Eli Lilly, Zepbound is the brand name for tirzepatide when employed for weight loss. When prescribed for diabetes, it goes by the name Mounjaro. Similar to semaglutide, the compound found in Ozempic and Wegovy, tirzepatide works by slowing down stomach emptying, leading to a quicker and prolonged feeling of fullness. Additionally, these drugs target the brain area that regulates appetite, reducing cravings. Tirzepatide, mimicking two hormones compared to semaglutide’s one, is believed to be more effective in inducing weight loss. In a 72-week clinical trial funded by Eli Lilly, participants with obesity taking the highest dose of tirzepatide experienced an average weight loss of around 18 percent.
For individuals already using Ozempic or Wegovy, the efficacy of these medications can vary from person to person. Dr. Janice Jin Hwang from the University of North Carolina School of Medicine emphasizes that factors like other health outcomes should be considered, especially for those at risk of heart failure or liver disease. The risks and benefits of switching medications need careful evaluation, as some individuals may experience excessive weight loss, particularly older people prone to muscle mass reduction.
The issue of insurance coverage and out-of-pocket costs remains a variable, with different plans potentially covering Zepbound for those meeting the FDA’s criteria. Eli Lilly expects Zepbound to be available in the U.S. by the year-end, with a list price of $1,059.87.
As with any medication, tirzepatide is associated with side effects, primarily gastrointestinal issues according to an Eli Lilly-funded study. The highest dose of tirzepatide resulted in approximately one-third of participants experiencing nausea and one-fifth reporting diarrhea. Other reported side effects included abdominal pain, vomiting, constipation, headache, dizziness, burping, hair loss, and gastroesophageal reflux disease, as outlined in the FDA approval. However, due to the novelty of tirzepatide, its long-term effects are not yet fully understood, and individuals using such drugs for weight loss are generally advised to continue them indefinitely.