Efficacy of hemodialysis and the effects of certain displacing agents on plasma protein binding of sulfamethoxazole and sulfaphenazole in patients with chronic renal failure.

Abstract

The binding of sulfamethoxazole and sulfaphenazole to the plasma protein of 7 patients with chronic renal failure, undergoing chronic hemodialysis, was studied by the equilibrium dialysis method and the results were compared with those for 12 normal subjects. The binding percentages of the two sulfonamides were found to be impared in the patients'plasma as compared with normal plasma. The binding percentages increased in the patients'plasma after hemodialysis except in the cases of 2 patients for sulfamethoxazole (SMX) and 1 patient for sulfaphenanzole (SPH). The effect of hemodialysis on drug protein binding was examined by calculating the percentage displacement of bound sulfonamides by oxyphenbutazone and sulfinpyrazone. Percentage displacements were higher in the patients' plasma than in normal plasma. The percentage displacement decreased in the patients'plasma after hemodialysis, except in the cases of 1 patient for SMX and 1 patient for SPH. Such a decrease in the percentage displacement after hemodialysis suggests that the drug binding activity of plasma albumin can be improved through hemodialysis for patients with chronic renal failure.