Safety profiles of new xanthine oxidase inhibitors: A post-marketing study

The development of new xanthine oxidase (XO) inhibitors, such as febuxostat and topiroxostat, could offer an alternative to treatment with allopurinol. The purpose of this study was to compare safety profiles of new XO inhibitors with allopurinol using a spontaneous reporting system database.

A retrospective pharmacovigilance disproportionality analysis was conducted using the Japanese Adverse Drug Event Report database. Adverse event reports submitted to the Pharmaceuticals and Medical Devices Agency were analyzed, and the reporting odds ratio (ROR) and 95% confidence interval (CI) for each adverse event were calculated.

Among 7,305 reports of adverse events associated with XO inhibitors, 64.5% involved males, who were frequently in their 70s (25.9%). A large number of skin-related adverse events were detected with the use of allopurinol, but not with febuxostat or topiroxostat. As for individual XO inhibitors, the signal values showing associations between drug reaction with eosinophilia and systemic symptoms (DRESS) and allopurinol, drug-induced liver injury and febuxostat, and blood urea increase and topiroxostat were noteworthy.

The strength of the associations of XO inhibitors with adverse events is variable, and further studies are required to evaluate the identified signals.