When giving 100 mg allopurinol and 20 mg benzbromarone in a fixed combination we found that the oxipurinol levels differed at 0 and after 4 h from those after administration of 100 mg allopurinol; the oxipurinol clearance is increased; benzbromarone increased the glomerular filtration rate as well as the urine volume. 2. The urate serum levels are decreased under additional administration of benzbromarone, the urate clearance is increased; urate levels in serum dropped slower than under monotherapy with alloprinol and increased again within the last 12 h.
