Effect of probenecid on oxypurines in plasma

Probenecid decreased the plasma concentration of oxypurines (hypoxanthine and xanthine) but did not increase the renal excretion of oxypurines. However, the concentrations of hypoxanthine and nucleotides (inosine monophosphate, adenosine monophosphate, adenosine diphosphate, adenosine triphosphate, guanosine diphosphate and guanosine triphosphate) in red blood cells did not change after the administration of probenecid. In addition, the drug did not inhibit adenosine deaminase, purine nucleoside phosphorylase, hypoxanthine guanine phosphoribosyl transferase and xanthine oxidase in vitro. These results suggested that the rapid fall of plasma concentration of uric acid due to the potent uricosuric action of probenecid resulted in the fall of plasma concentration of oxypurines.