Binding of drugs to human serum albumin XVII: Irreversible binding of mercaptopurine to human serum proteins.

Studies on the binding of mercaptopurine to human serum, human serum albumin or orosomucoid gave varying results, with binding ranging from 20 to 90%. Binding has been shown to be affected by oxidizing agents, which increase binding at low concentrations, and by reducing agents, which decrease binding. Repeated equilibrium dialyses and gel filtration experiments indicated that mercaptopurine is partly irreversibly bound to serum proteins. This binding is oxidation dependent and probably involves the sulfhydryl group of the drug.