Clinical Question

Does tirzepatide (Mounjaro) safely help patients lose more weight than placebo?

Bottom Line

In patients with obesity without diabetes mellitus, those taking tirzepatide lost 15% to 21% of their body weight (compared with 3% for those taking placebo) over a 72-week period. The lowest cost on goodrx.com was $967 per month for four 10-mg cartridges for injection. (Level of Evidence = 1b)

Synopsis

Tirzepatide is a glucagon-like peptide-1 receptor agonist developed to treat type 2 diabetes. The study identified adults with a body mass index greater than 30.0 kg per m² or greater than 27.0 kg per m² with at least one weight-related complication, such as hypertension, sleep apnea, cardiovascular disease, or dyslipidemia. Patients with diabetes were excluded. The mean age of the 2,539 patients was 45 years, 67% were women, and 60% had a body mass index greater than 35.0 kg per m². Allocation concealment was not described, but groups were balanced at the start of the study. The patients were randomized to receive 5, 10, or 15 mg of tirzepatide or matching placebo injection once weekly. Approximately 86% of participants completed the 72-week study. The reduction in weight was 15% in the 5-mg group, 19.5% in the 10-mg group, 20.9% in the 15-mg group, and 3.1% in the placebo group. Reductions also occurred in metabolic markers, such as systolic blood pressure (6.2 mm Hg) and low-density lipoprotein cholesterol (4.2 mg per dL [0.15 mmol per L]), in the tirzepatide groups. Serious adverse events were rare and evenly distributed among groups. Discontinuation due to adverse events was 2.6% in the placebo group and 4.3% to 7.1% in the tirzepatide groups.