FORMULATION DEVELOPMENT AND EVALUATION OF CHITOSAN BASED MUCOADHESIVE BILAYERED BUCCAL PATCHES OF CARVEDILOL

Carvedilol is a non-selective β blocker with α1 blocking activity used in the treatment of congestive heart failure, high blood pressure, and left ventricular dysfunction. Following administration by the oral route, it undergoes extensive first-pass metabolism resulting in low bioavailability of 25-35%. The aim of the present study was to incorporate carvedilol in bilayered chitosan containing mucoadhesive buccal patches to ensure unidirectional drug release. Buccal administration circumvents hepatic first-pass metabolism, as the drug directly enters into the systemic circulation through the buccal mucosa, thereby increasing systemic bioavailability. The patches were prepared using solvent casting method. Chitosan was used as a mucoadhesive polymer as well as the base matrix for the drug. To improve film properties of the patches, PVP was incorporated in all the formulations. An impermeable backing layer of ethylcellulose was used to ensure the unidirectional release of the drug. The compatibility of carvedilol and polymers was confirmed by DSC and FTIR. Bilayered patches were evaluated for various physicochemical parameters like appearance, weight and thickness, folding endurance, tensile strength, surface pH, swelling, drug content uniformity, in-vitro drug release, mucoadhesive strength, ex-vivo mucoadhesion time and ex-vivo permeability studies. The morphology of the patches was studied by SEM. Stability studies of the optimized patches were carried out at 40 ºC / 75% RH for 3 months as well as in natural human saliva. The results indicate that suitable bilayered buccal patches with chitosan as a mucoadhesive polymer can be prepared successfully to ensure satisfactory unidirectional release of Carvedilol with adequate mucoadhesion.