The Effect of Dialysis on the Protein Binding of Drugs in the Plasma of Patients with Acute Renal Failure

Abstract:The protein‐bound fraction of acetylsalicylic acid, salicylic acid, phenylbutazone, diphenylhydantoin, sulphadiazine and thiopental was found to be increased in blood plasma afterin vitrodialysis of plasma from blood donors and also in the plasma of surgical patients suffering from acute renal failure. The concentrations of the drugs ranged from 50 to 600 μg/ml. The increments (in μg drug bound/mg albumin) were significantly larger in the patient‐plasmas than in the donor plasmas for diphenylhydantoin, phenylbutazone and sulphadiazine. The albumin‐bound fraction of all the six drugs was significantly greater when human serum albumin and the drug were dissolved in patient‐plasma ultrafiltrate which had previously been dialysed against a Ringer‐solution, than when albumin and the drug were dissolved in undialysed patient plasma ultrafiltrate. For ultrafiltrate prepared from donor plasma only acetylsalicylic acid showed significantly increased binding in dialysed ultrafiltrate. The increments (in μg drug bound/mg albumin) were significantly greater in the patient ultrafiltrates than in the donor ultrafiltrates for thiopental, salicylic acid, phenylbutazone and sulphadiazine. The drug‐binding capacity of the protein in dialysed patient plasma for four of the drugs was significantly lower than the drug‐binding capacity of albumin added in the same concentration to the dialysed plasma ultrafiltrate. For two drugs, diphenylhydantoin and thiopental, the differences in the same direction were not statistically significant. In donor plasma, the binding to genuine plasma protein was not different from the binding to added albumin.