Per-oral extended-release bioadhesive tablet formulation of verapamil HCl.

The objective of this study was to formulate a hydrogel-forming bioadhesive drug delivery system for oral administration of verapamil HCl (VP). This system is a non-distintegrating gastro-retentive tablet to allow continuous slow release of VP in the stomach medium where it is more soluble. Different formulate of VP tablets were prepared by compression using various proportions of hydroxypropyl cellulose (HPC) and carbopol 934p (CP). The effect of polymer concentration on the release profile, water uptake and in vitro bioadhesion was studied. Five formulae (F3-F7) exhibited slow release profiles. Formulations F6 (40% HPC and 30% CP) and F7 (40% HPC and 40% CP) had the slowest. They showed 63.6 and 52.2% drug release, respectively, after 12 hours. The kinetic analysis of the release data demonstrated that the bigbest linearity were achieved when data fitted in Higuchi equation rather than zero or first order equations. They had n values close to 0.5 that confirming their Higuchi diffusion. F3 showed the highest swelling index (101.2%), however, the detachment force was intermediate (1.427 N/cm2). Formulae (F4-F7) showed relatively strong in-vitro bioadhesive force. They had detachment forces higher than 1 N/cm2. In general, a delay in drug release and an increase in the in-vitro bioadhesion was seen with the increase in both polymer concentrations. The in vitro data revealed that Formulae F4-F7 served the dual purpose of bioadhesion and sustained release.