DISSOLUTION TESTING FOR SUSTAINED OR CONTROLLED-RELEASE ORAL DOSAGE FORMS AND CORRELATION WITH IN-VIVO DATA - CHALLENGES AND OPPORTUNITIES

Despite the fact that dissolution tests were first introduced to chara cterise the release profile of low solubility (< 1%) drugs in aqueous media, the emphasis is now to adopt dissolution tests in monographs of almost all oral solid dosage forms in most pharmacopoeias. This is at tributable mainly to the growing demand by both regulatory authorities and pharmaceutical industries of more in vivo predictability of the r elease and absorption behaviours of drug(s) from the dosage form by me ans of in vitro tests, i.e. invitro-in vivo correlation. Dissolution t esting is also essential in various stages of formulation development for screening and proper assessment of different formulations. Althoug h dissolution tests have been successfully implemented on conventional dosage forms, there are enormous difficulties in establishing proper dissolution test conditions and parameters for testing sustained or co ntrolled release oral dosage forms because of prolonged gastrointestin al residence of the dosage form and variabilities in physiological con ditions of the gastrointestinal tract. This review focuses on the chal lenges faced by formulation scientists and regulatory authorities in g eneralising the dissolution test conditions and parameters for testing sustained or controlled release dosage forms, and describes some rece nt trends and progress in overcoming some of these challenges.