Tirzepatide beneficial for shedding pounds in obese adults

Once-weekly treatment with tirzepatide in adults with obesity appears to yield substantial and sustained reductions in body weight, according to the phase III SURMOUNT-1 trial.

SURMOUNT-1 involved 2,539 adults with a body mass index (BMI) of ≥30 kg/m² or ≥27 kg/m² or more and at least one weight-related complication, excluding diabetes. They were randomized to receive once-weekly, subcutaneous tirzepatide at 5, 10, or 15 mg, or placebo for 72 weeks, including a 20-week dose-escalation period.

Efficacy was assessed based on the coprimary endpoints of the percentage change in weight from baseline and a weight reduction of ≥5 percent.

The baseline mean body weight of the population was 104.8 kg, and 94.5 percent of the participants had a BMI of ≥30 kg/m². 

At week 72, the mean percentage change in weight was greater across the tirzepatide dose groups vs the placebo group: −15.0 percent (95 percent confidence interval [CI], −15.9 to −14.2) with the 5-mg tirzepatide dose, −19.5 percent (95 percent CI, −20.4 to −18.5) with the 10-mg dose, and −20.9 percent (95 percent CI, −21.8 to −19.9) with the 15-mg dose vs −3.1 percent (95 precent CI, −4.3 to −1.9) with placebo (p<0.001 for all comparisons).

The same was true for the percentage of participants whose weight decreased by ≥5 percent: 85 percent (95 percent CI, 82–89) with 5 mg, 89 percent (95 percent CI, 86–92) with 10 mg, and 91 percent (95 percent CI, 88–94) with 15 mg of tirzepatide vs 35 percent (95 percent CI, 30–39) with placebo.

Of note, 50 percent (95 percent CI, 46–54) and 57 percent (95 percent CI, 53–61) of participants in the 10- and 15-mg groups achieved a reduction in body weight of ≥20 percent as compared with only 3 percent (95 percent CI, 1–5) in the placebo group (p<0.001 for all comparisons).

Parallel improvements in all prespecified cardiometabolic measures were seen with tirzepatide.

The most common adverse events with tirzepatide were gastrointestinal, occurring primarily during dose escalation. These events were mostly mild to moderate in severity. Adverse events led to treatment discontinuation in 4.3 percent, 7.1 percent, 6.2 percent, and 2.6 percent of participants in the 5-, 10-, and 15-mg tirzepatide and placebo groups, respectively.