Interindividual Differences in the Protein Binding of Sulfonamides: The Effect of Disease and Drugs 1,2

Abstract: The variation in the plasma protein binding of sulfonamides in healthy adults was minimal. Additional evidence for consistency in binding came from a literature survey in which it was found that the plasma protein binding of several sulfonamides in man and laboratory animals was remarkably similar as reported by investigators from different countries. Some hospitalized patients, however, do show a binding deficiency which may be due to an interaction between drugs, disease and altered plasma proteins. Several drugs were found to compete with the sulfonamide for the same binding sites on the protein (albumin) molecule. The plasma protein binding of a sulfonamide in six anephric patients was studied before and after haemodialysis. As expected all showed a deficiency in binding. Unexpectedly, however, the binding was less in the post-dialysis plasma sample in three patients. In some patients there appeared to be a qualitative and a quantitative change in the binding sites on the protein. More definitive studies are needed with plasma protein fractions from healthy and ill subjects in the presence and absence of drugs. This may lead to a better understanding of the side effects to some drugs and could result in the development of useful displacing agents.