Formulation and evaluation of mucoadhesive buccal films impregnated with carvedilol nanosuspension: a potential approach for delivery of drugs having high first-pass metabolism.

Context: Mucoadhesive buccal films containing three layers (mucoadhesive layer, nanosuspension containing layer and backing membrane) were incorporated with carvedilol nanosuspension. Objective: Formulation and evaluation of nanosuspension incorporated mucoadhesive buccal films of carvedilol for bioavailability enhancement by avoiding first-pass metabolism. Methods: Carvedilol-loaded nanosuspension was prepared by a precipitation-ultrasonication method with varying concentrations of the polymer. The formulation was analyzed for size, size distribution, surface charge and morphology. Optimized nanosuspension was incorporated into drug gel layer which was sandwiched between a mucoadhesive layer and a backing layer to form tri-layered buccal films. They were evaluated for their physical, mechanical and bioadhesive parameters followed by in vitro and in vivo studies. Results and discussion: Nanosuspension showed a negative zeta potential (-17.21 mV) with a diameter of around 495 nm and a polydispersity index of 0.203. Nanosuspension incorporated drug gel layer (62.4% drug loading) was optimized to contain 3% HPMC and 50 mg Carbopol 934P. The mucoadhesive layer and the backing layer were optimized to contain 3% HPMC and 1% ethyl cellulose, respectively. In vitro drug release was 69% and 62.4% in 9 h across synthetic membrane and porcine buccal mucosa, respectively. In vivo studies conducted in rabbit model showed 916% increase in the relative bioavailability in comparison to marketed oral tablet formulation. The C-max and T-max of the prepared formulation increased due to increased surface area of drug and also by-passing hepatic metabolism. Conclusion: The drug delivery system has been designed as a novel platform for potential buccal delivery of drugs having high first-pass metabolism.