EFFECT OF ALLOPURINOL AND BENZBROMARONE ON THE CONCENTRATION OF URIDINE IN PLASMA

To investigate whether allopurinol and benzbromarone affect the concen tration of uridine in plasma, allopurinol or benzbromarone were admini stered to patients with gout for 3 to 6 months. Allopurinol decreased the concentrations of uridine and uric acid in plasma and the urinary excretion of uric acid, but increased the plasma concentration and uri nary excretion of oxypurines and orotidine. Benzbromarone decreased th e concentration of uric acid in plasma and increased the excretion of uric acid in urine. However, it did not affect the plasma concentratio n of uridine dr oxypurines or the urinary excretion of oxypurines or o rotidine. These results suggest that orotidilytic decarboxylase was in hibited by allopurinol and oxypurinol ribonucleotides and/or that phos phoribosyl pyrophosphate (PRPP) was consumed by conversion from hypoxa nthine, allopurinol, and oxypurinol to the respective ribonucleotides, resulting in a decrease in the de novo synthesis of pyrimidine leadin g to the decreased concentration of uridine in plasma. Furthermore, it was suggested that benzbromarone did not affect the de novo synthesis of pyrimidine or purine. Copyright (C) 1997 by W.B. Saunders Company.