Studies on Drug Nonequivalence. X. Bioavailability of 6-Mercaptopurine Polymorphs

Abstract

The gastrointestinal absorption of 6-mercaptopurine (6-MP) polymorphs was studied in rabbits, and their absorption kinetics were analyzed. Form III of 6-MP was absorbed more efficiently from the gastrointestinal tract than form I. It was found that the absorption kinetics after oral administration of 6-MP could be satisfactorily accounted for by a two-compartment model with two consecutive first-order input steps. Form III had an extent of bioavailability about 1.5 times greater than that of form I. This result may be attributed to a difference of K1 and/or Ka between the polymorphic forms I and III. © 1981, The Pharmaceutical Society of Japan. All rights reserved.