Utilization patterns of antihyperuricemic agents following safety announcement on allopurinol and benzbromarone by Taiwan Food and Drug Administration

OBJECTIVE: The purpose of this study is to evaluate the utilization of four approved antihyperuricemic agents in Taiwan before and after two safety announcements rescinded an indication for allopurinol and added a warning on benzbromarone-induced hepatotoxicity in the year 2005.

METHODS: An interrupted time series design and segmented regression models were used to examine impacts of the safety announcements on the utilization of allopurinol, benzbromarone, probenecid, or sulfinpyrazone. All outpatient prescriptions of the four antihyperuricemic agents were extracted from a longitudinal cohort dataset with 1000000 individuals randomly sampled from the National Health Insurance Research Database. We examined utilization patterns of antihyperuricemic agents before and after the policy intervention (i.e., safety announcements and labeling changes of allopurinol and benzbromarone) in the year 2005.

RESULTS: Following the safety announcements, there was a reduction in the number of allopurinol users in the first year of intervention (-95.82 users per 100000 persons, 95%CI, [-166.84, -24.80]) and a continuous reduction afterward at a rate of -53.17 per 100000 persons per year. The utilization of benzbromarone grew steadily before 2005 but decreased drastically after the intervention, with a 30.12% reduction in the number of users by the end of year 2008. There was no commensurate change in the number of probenecid or sulfinpyrazone users after the intervention.

CONCLUSIONS: Further research is required to evaluate the direct impacts of the safety announcements on clinical outcomes, treatment costs, and patient's quality of life.