FDA greenlights new obesity treatment

Science and Health

The US Food and Drug Administration has granted approval for the Zepbound (tirzepatide) injection, a groundbreaking injection leading to weight loss. 

Tirzepatide, the active ingredient in Zepbound, is already approved under the trade name Mounjaro to be used along with diet and exercise to help improve blood sugar (glucose) in adults with type 2 diabetes mellitus, FDA stated. 

Preliminary studies have revealed its ability to reduce body weight by up to 26% in individuals classified as obese (with a BMI index of 30) or overweight (with a BMI index of 27). The injection, developed by Eli Lilly, is currently allowed in Israel for diabetes treatment and is under consideration for inclusion in the upcoming drug basket.

“Obesity and overweight are serious conditions that can be associated with some of the leading causes of death such as heart disease, stroke and diabetes,” said John Sharretts, M.D., director of the Division of Diabetes, Lipid Disorders, and Obesity in the FDA’s Center for Drug Evaluation and Research. “In light of increasing rates of both obesity and overweight in the United States, today’s approval addresses an unmet medical need.” 

An American epidemic

Approximately 70% of American adults grapple with obesity or being overweight, often accompanied by weight-related health concerns. Shedding 5-10% of body weight through diet and exercise has demonstrated a reduced risk of cardiovascular disease in this population.

Mounjaro’s effectiveness in weight loss and maintenance, when combined with a reduced-calorie diet and increased physical activity, was evident in two randomized, double-blind, placebo-controlled studies. These studies, spanning 72 weeks, involved 2,519 patients receiving 5 mg, 10 mg, or 15 mg of Mounjaro weekly, compared to 958 patients on weekly placebo injections. Results showed a statistically significant decrease in body weight for those receiving Maugnero at all doses compared to the placebo group.

Credit: Ili Lilly


In one study with an initial average participant weight of 105 kg, those on the highest approved dose of Mounjaro (15 mg once a week) lost an average of 18% of their body weight compared to the placebo group.

Despite its promising results, Maugnero comes with cautionary notes due to potential side effects. The drug activates receptors for gut-secreted hormones, reducing appetite and food intake. Administered by a subcutaneous injection weekly, the dose should be increased over 4 to 20 weeks to reach the target dose of 5 mg, 10 mg, or 15 mg weekly.

Like other weight loss drugs in its category, Mounjaro poses potentially serious side effects. Individuals with a history of severe gastroparesis should avoid the drug, according to the FDA. Companies Eli Lilly and Novo Nordisk, creators of obesity drugs Wegovy and Ozempic, previously faced claims linking their drugs to stomach paralysis. The FDA recently recommended adding a warning for this condition to Ozempic’s consumer information leaflet.

The FDA also highlighted higher risks for individuals with a history of thyroid cancer, pancreatitis, or serious gastrointestinal disease when using Mounjaro. Combining Mounjaro with other slimming injections is also discouraged due to insufficient studies on potential interactions.