179 RENAL EXCRETIONS OF OXYPURINOL AND OXYPURINES - EFFECTS OF PYRAZINAMIDE, PROBENECID AND BENZBROMARONE -

The renal handlings of oxypurinol and oxypurines by normal subjects after intake of allopurinol were investigated by studies on the influences of uricosuric agents (probenecid and benzbromarone) and pyrazinamide. Pyrazinamide decreased the fractional clearance of oxypurinol, hypoxanthine and xanthine 0.46-, 0.52- and 0.40-fold, respectively. Probenecid increased the fractional clearance of oxypurinol 1.8-fold, decreased that of xanthine 0.61-fold and did not affect that of hypoxanthine. Benzbromarone increased the fractional clearance of oxypurinol 2.17-fold but did not affect those of hypoxanthine and xanthine. These results suggest that oxypurinol is reabsorbed at least at a postsecretory site of the renal tubules, that the main renal transport of xanthine is secretory when conversion of oxypurines to uric acid is decreased and that the main renal transport of hypoxanthine that is not affected by these three agents may occur when conversion of oxypurines to uric acid is decreased.