Postmarketing Surveillance Study of the Efficacy and Safety of Phentermine in Patients with Obesity

BACKGROUND: Obesity is a complex problem that is now considered a chronic metabolic disease. In Korea, phentermine has been widely used for the treatment of obesity in the primary care setting since 2004. However, there have been very few studies on the safety and efficacy of phentermine. To investigate the safety and efficacy of this drug, a postmarketing surveillance study was performed. METHODS: A total of 795 patients with obesity (body mass index ≥ 25 kg/m(2)) were enrolled from 30 primary care centers in Korea from September 2006 to November 2007. Patients were examined to ascertain safety and efficacy at 4-, 8-, and 12-week intervals. The criterion for efficacy was defined as a weight loss ≥ 5% of body weight. RESULTS: Of the 795 enrolled patients, 735 (92.5%) were evaluated in safety assessments and 711 (89.4%) was included in efficacy assessments. A total of 266 adverse events (AEs) were reported by 218 patients (30.6%), and no serious AEs were reported. Among 711 patients, 324 patients (45.6%) lost ≥ 5% of their body weight. The mean weight loss was 3.8 ± 4.0 kg. CONCLUSION: AEs are commonly associated with phentermine, even though phentermine is effective for weight loss and relatively well-tolerated.