Long-Term Safety and Effectiveness of the Xanthine Oxidoreductase Inhibitor, Topiroxostat in Japanese Hyperuricemic Patients with or Without Gout: A 54-week Open-label, Multicenter, Post-marketing Observational Study

Background and Objectives Topiroxostat, a selective xanthine oxidoreductase inhibitor, is used for the management of hyperuricemic patients with or without gout in Japan. Accumulating evidence has demonstrated the efficacy of topiroxostat for the treatment of hyperuricemia with or without gout. However, the safety and efficacy of topiroxostat in the clinical setting remain unclear, and there is little large-scale clinical evidence. We conducted a post-marketing observational study over 54 weeks. Patients and Methods Patients were centrally enrolled, and case report forms of 4491 patients were collected between April 2014 and March 2019 from 825 medical sites. Results Overall, 4329 patients were assessed for safety and 4253 patients for effectiveness. The overall incidence of adverse drug reactions was 6.95%, and the incidence rates of adverse drug reactions of gouty arthritis, hepatic dysfunction, and skin disorders, which are of special interest in this study, were 0.79%, 1.73%, and 0.95%, respectively. No case of serious gouty arthritis was observed. Serum urate levels decreased stably over time and showed a significant reduction rate at 54 weeks (21.19% +/- 22.07%) and on the final visit (19.91% +/- 23.35%) compared to the baseline. The rates for subjects who achieved serum uric acid levels <= 6.0 mg/dL at 18 and 54 weeks after administration were 43.80% and 48.28%, respectively. Conclusions This study suggests that there is no particular concern about adverse drug reactions or the efficacy of topiroxostat for hyperuricemic patients with or without gout in a post-marketing setting in Japan.