A recent phase 3 clinical trial on tirzepatide, sold as Mounjaro, has revealed that when taken after initial weight loss achieved through diet and lifestyle changes, the drug can lead to further significant weight reduction.
Semaglutide, sold as Ozempic and Wegovy, has been making headlines for its weight loss properties. Tirzepatide, a competitor to semaglutide, has been undergoing phase 3 clinical trials to assess its effectiveness in promoting weight loss.
This particular trial, known as the SURMOUNT-3 study, is the third phase of clinical testing for tirzepatide. The findings from the 72-week study, sponsored by pharmaceutical company Eli Lilly, indicate that tirzepatide resulted in additional weight loss among individuals who had already lost 5% or more of their body weight through lifestyle interventions prior to starting the drug.
Gitanjali Srivastava, one of the study’s co-authors, expressed excitement about the results of the SURMOUNT-3 trial. The medication has already proven highly effective in treating type 2 diabetes, but this research provides solid evidence that it is also extremely effective in achieving significant and life-changing weight loss in conjunction with a low-calorie diet, exercise, and behavioral counseling.
Tirzepatide mimics the actions of two hormones—glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP)—which work together to stimulate insulin secretion and slow stomach emptying, resulting in a prolonged feeling of fullness.
Prior to receiving either the drug or a placebo, the 806 participants underwent a 12-week “lead-in period” of intensive lifestyle intervention. This intervention included a reduced-calorie diet, at least 150 minutes of physical activity per week, and frequent behavioral counseling.
Participants had at least one obesity-related complication, excluding diabetes. Out of the 579 participants who achieved a 5% reduction in body weight at the end of the lead-in period, they were randomly assigned to receive either tirzepatide or a placebo. The 5% threshold was chosen because research has shown that reducing baseline body weight by 5% to 10% decreases the risk of developing type 2 diabetes and improves cardiometabolic risk factors such as blood pressure and other obesity-related complications.
The initial dose of tirzepatide was 2.5 mg, which gradually increased by 2.5 mg every four weeks until reaching a maximum tolerated dose of either 10 mg or 15 mg per week. At the start of the study, the average body weight was 241.4 lb (109.5 kg). By the end of the 12-week lead-in period, participants had achieved an average weight loss of 6.9%, or 16.8 lb (7.6 kg).
Participants in the tirzepatide group experienced an additional average weight loss of 21.1%. Over the course of the entire study, which spanned 84 weeks, they achieved a total average weight loss of 26.6% or 64.4 lb (29.2 kg). In comparison, participants in the placebo group attained a total average weight loss of 3.8% or 9.0 lb (4.1 kg) during the same period.
The weight loss induced by tirzepatide led to benefits such as lower blood pressure, improved blood lipid levels, and better blood glucose control compared to the placebo group. The most frequently reported adverse events were gastrointestinal in nature, including mild to moderate nausea, diarrhea, and constipation, which mainly occurred during dose escalation.
Srivastava believes that tirzepatide, along with semaglutide 2.4 mg once weekly for adults with overweight or obesity, marks a new era of incretin-based therapies that can achieve weight loss exceeding the clinically significant 5% threshold. These innovative therapies are rapidly changing the landscape of obesity treatment, with more options currently in development. For individuals struggling with obesity, there is now hope backed by scientific evidence.
While Mounjaro, Ozempic, and Wegovy all contribute to weight loss, only Wegovy has received FDA approval for chronic weight management. Mounjaro and Ozempic are currently approved solely for their original purpose of controlling blood sugar levels in individuals with type 2 diabetes.
1. Source: Coherent Market Insights, Public sources, Desk research
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