Predicting in vivo absorption behavior of oral modified release dosage forms containing pH-dependent poorly soluble drugs using a novel pH-adjusted biphasic in vitro dissolution test.

The focus of in vitro dissolution testing during early development of modified release (MR) formulations is to provide predictive estimates of drug release in respect to in vivo performance of a drug product. However, there are enormous challenges in MR drug development to establish proper dissolution conditions for a predictive test. To overcome limitations of dissolution testing at constant pH, a modified USP apparatus 2 was developed, combining biphasic dissolution with a pH-gradient in the aqueous dissolution medium.