Weekly tirzepatide injections for obese patients over a period of 72 weeks has been shown to give rise to large reductions in body weight
Weekly tirzepatide injections to patients with a body mass index (BMI) greater than 30 over a period of 72 weeks have been found to produce significant reductions in body weight. This was the conclusion of the SURMOUNT-1 trial according to the study’s investigators.
According to the World Health Organization (WHO), the terms, overweight and obesity are defined by abnormal or excessive fat accumulation and that present a risk to health. The terms are assessed with respect to body mass index such that individuals with a BMI > 25 are considered to be overweight and obese, where the BMI exceeds 30. Obesity is a global problem and using data from 2016, WHO estimates that 1.9 billion adults were overweight and 650 million obese and there is good evidence that a higher BMI is associated with an increased risk of all-cause mortality.
Tirzepatide is a novel, dual glucose-like peptide-1 and a glucose-dependent insulinotropic polypeptide GLP-1 receptor agonist, which has the potential to deliver clinically meaningful improvement in glycaemic control and body weight. In addition to glargine for example, weekly tirzepatide has been found to produce statistically significant improvements in glycaemic control in type 2 diabetic patients after 40 weeks as well as a reduction in body weight.
For the present trial, investigators undertook a double-blind, randomised, placebo-controlled trial in adults with a BMI of 30 or more, testing three doses (5, 10 and 15 mg) of weekly tirzepatide. In addition, to an elevated BMI, enrolled adults were also required to have at least one weight-related complication e.g., hypertension, dyslipidaemia or cardiovascular disease. Individuals were randomised 1:1:1:1 to weekly tirzepatide at a dose of 5, 10 or 15 mg or placebo and doses were administered for a period of 72 weeks as an adjunct to a lifestyle intervention, which included lifestyle counselling sessions and advice to undertake at least 150 minutes of physical exercise per week. The coprimary endpoints were the percentage change in body weight from baseline and a weigh reduction of 5% or more at week 72. Secondary endpoints included weight reductions or 10%, 15% and 20% or more at week 72.
Weekly tirzepatide and weight loss
A total of 2,539 individuals with a mean age of 44.9 years (67.5% female) were randomised to one of the four interventions. The mean baseline BMI for the whole cohort was 38 and 94.5% of participants had a BMI of 30 or higher.
The mean percentage change in body weight at week 72 was -15% for the 5mg dose, – 19.5% for 10mg and -20.9% with 15mg compared to -3.1% with placebo (p < 0.001 for all comparisons with placebo).
Overall, 57% of participants given 15mg tirzepatide had a 20% or more reduction in body weight.
The safety profile of the drug was excellent with adverse effects generally of mild to moderate severity and largely gastrointestinal in nature. Adverse effects leading to treatment discontinuation occurred in 6.2% of those given 15mg tirzepatide compared with 2.6% in the placebo group.
The authors concluded that once weekly tirzepatide resulted in substantial and sustained reductions in body weight.
Jastreboff AM et al. Tirzepatide Once Weekly for the Treatment of Obesity N Engl J Med 2022