ABSTRACT
RingCap is a patented, oral controlled-release drug delivery system. The dosage form is a capsule-shaped matrix tablet to which bands of insoluble material are applied circumferentially to the surface of the tablet (Fig. 1). These bands modify the release of drug from the tablet through the control of surface area [1,2]. In general, the release of drug from RingCap tablets is proportional to the surface area exposed to the dissolution media. This surface area changes over time as the area around the bands becomes hydrated and erodes creating new surface area. This new surface area can decrease, remain constant, or even increase with time. The exposed surface area is controlled by the number, width, and placement of bands of insoluble material applied to the tablets.
