Objectives: To compare the efficacy and tolerability of allopurinol 300-600 mg/day versus benzbromarone 100-200 mg/day to attain a target sUr ≤0.30 mmol/l (5 mg/dl).
Methods: A randomised, controlled, open-label, multi-centre trial in gout patients with renal function defined as cCrCl ≥50 ml/min. Patients were treated with 300 mg allopurinol or 100 mg benzbromarone once daily (stage 1). When sUr ≤0.30 mmol/l was not attained after 2 months, dosage was doubled to allopurinol 300 mg twice daily or benzbromarone 200 mg once daily (stage 2). Primary endpoint was treatment success in either of both stages, defined as clinical tolerability and attainment of biochemical target serum urate concentration.
Results: Sixty-five patients were enrolled in stage 1, 36 patients received allopurinol and 29 received benzbromarone. Fifty-five patients (85%) were evaluated for analysis of stage 1. At stage 1, the success rates are 8/31=0.26 (26%) and 13/25=0.52 (52%), and difference is 0-0.26 (CI 95% from -0.486 to -0.005), p=0.049. At stage 2, the success rates are 21/27=0.78 (78%) and 18/23=0.78 (78%), and difference is -0.005, (CI 95% from -0.223 to 0.220), p=1.00.Two patients stopped allopurinol and 3 patients stopped benzbromarone because of adverse drug reactions (ADR).
Conclusion: Increase of allopurinol dosage from 300 mg to 600 mg/day and benzbromarone dosage from 100 mg to 200 mg/day according to target sUr, gives significantly higher success rates (both 78% success in sUr ≤0.30 mmol/l). No significant differences in treatment success between benzbromarone and allopurinol groups were found after dosage escalation (controlled-trials.com number ISRCTN49563848).