Foundation review: MRI as a tool for evaluation of oral controlled release dosage forms

The magnetic resonance imaging (MRI) studies of controlled-release (CR) dosage forms can be roughly divided into two groups. The first comprises studies performed in static conditions (small solvent volumes and ambient temperature). Such studies have provided insight into molecular phenomena in hydrating polymeric matrices. The second group covers research performed in dynamic conditions (medium flow or stirring) related to drug dissolution. An important issue is supplementation of the MRI results with data obtained by complementary techniques, such as Xray microtomography (mu CT). As we discuss here, an understanding of the mechanism underlying the release of the drug from the dosage form will lead to the development of detailed, molecularly defined, CR dosage forms.