Riboflavin distribution and elimination in two functionally anephric human patients

Pharmacokinetic studies in normal human subjects have suggested that probenecid modifies appreciably the distribution in the body of riboflavin and certain drugs. To exclude the effects of probenecid on renal excretion, the distribution and elimination of riboflavin with and without probenecid were studied in two functionally anephric patients during hemodialysis. A pharmacokinetic analysis of the time course of plasma levels of the vitamin, based on a two‐compartment open model, indicates no appreciable effect of probenecid on the distribution and transfer rate constants of riboflavin. Riboflavin was eliminated more slowly by hemodialysis of the patients than by renal excretion in normal subjects. The rate of removal of riboflavin by hemodialysis appears to be primarily a function of the rate of blood flow through the dialyzer.