Efficacy of phentermine/topiramate extended release in weight management and metabolic profiles: A multicentre study in South Korea

Abstract

Aims: Clinical trials have demonstrated the effectiveness of the phentermine and topiramate combination in weight management. This research evaluated the efficacy and safety of phentermine/topiramate extended release (ER) for weight management, focusing on alterations in body weight and metabolic parameters in routine clinical practice. Materials and Methods: We retrospectively included people with obesity who initiated phentermine/topiramate ER between January 2020 and April 2023 at 10 tertiary hospitals in South Korea. The study assessed body weight changes at 5-6 months and for those who continued, at 12 months, along with metabolic parameters. Total body weight was measured using calibrated electronic scales with participants in light indoor clothing. Results: The cohort included 1839 patients (540 men and 1299 women), with a 5-6-month continuation rate of 48%. At 5-6 months, the mean weight reduction was 7.9%, with sex-specific losses of 7.1% in men and 8.2% in women. Over 56% of participants achieved more than 5% weight loss, with 23% exceeding a 10% reduction. Younger participants, women and those with moderate to severe obesity exhibited more pronounced weight loss compared to older men and individuals with mild obesity, respectively. Concurrently, phentermine/topiramate ER treatment improved glucose regulation, lipid profiles and decreased blood pressure: the HbA1c decreased by 0.4 +/- 0.9%, low-density lipoprotein (LDL) cholesterol by 10 +/- 32 mg/dL and systolic blood pressure by 6 +/- 15 mmHg (all p < 0.001). Treatment was well-tolerated, with a 15% incidence of mild adverse events like paresthesia, dry mouth and insomnia. At 12 months, patients who persisted in treatment (21%) experienced an average weight loss of 9.6%, with 65% surpassing a 5% weight loss. Conclusion: The study suggests phentermine/topiramate ER is an effective option for obesity management in a South Korean population, though long-term adherence remains a challenge.