Evaluation of the efficacy and safety of controlled-release phentermine/topiramate in adults with obesity in Korea: A randomized, double-blind, placebo-controlled, phase 4 trial (QUEEN's study)

Aims: This study evaluated the efficacy and safety of a combination of phentermine and delayed-release topiramate (PHEN/TPM CR) versus placebo as an adjunct to standard lifestyle recommendations in Korean adults. Materials and Methods: This 56-week, randomized, double-blind, placebo-controlled, phase 4 trial enrolled adults (age 19–70 years) with obesity (BMI ≥ 25 kg/m²) at eight sites in South Korea. After a 12-week lifestyle programme, participants were randomly assigned in a 1:1 ratio to receive PHEN/TPM CR or placebo. PHEN/TPM CR was commenced at 3.75 mg/23 mg daily for 14 days and increased to 7.5 mg/46 mg daily, and to 15 mg/92 mg if 3% weight loss was not achieved after 12 weeks. The primary outcomes were percentage change in body weight from baseline to Week 56. Results: A total of 232 participants underwent randomization. At 56 weeks, the percentage change in body weight was −8.3% with PHEN/TPM CR and −2.3% with placebo (treatment difference −6.1%; 95% confidence interval [CI], −7.7 to −4.5, p < 0.001). Participants receiving PHEN/TPM CR were more likely to achieve ≥5% weight loss compared with those receiving placebo (68.5% vs. 25.0%, odds ratio [OR], 6.4; 95% CI, 3.5 to 11.6; p < 0.001). Dizziness, paraesthesia and dry mouth were more common in the PHEN/TPM CR group, although most adverse events were mild or moderate. Conclusions: Administration of PHEN/TPM CR plus lifestyle intervention in Korean adults with obesity resulted in a greater reduction in body weight and adiposity than lifestyle intervention alone.