Formulation and In Vivo Evaluation of Mucoadhesive Buccal Tablets of Carvedilol

Abstract

In present study we studied the feasibility of preparing mucoadhesive buccal delivery systems containing carvedilol to improve drug residence time on buccal mucosa and drug dissolution rate, to circumvent the first-pass metabolism and quick drug entry into the systemic circulation. Bilayer buccal tablets of carvedilol prepared using controlled release and mucoadhesive polymers (hydroxypropyl methylcellulose 15 cps, 50 cps, K4M and Carbopol 934p) along with impermeable backing layer (ethyl cellulose). 15 formulations were developed with varying concentrations of polymers. The designed tablets were evaluated for tablet size, shape, in vitro drug release, stability studies, bioavailability studies and drug-excipients interaction (FTIR). Among the 15 formulations, F151 containing hydroxypropyl methylcellulose 15 cps (48% w/w of matrix layer), Carbopol 934p (2% w/w of matrix layer) and mannitol (channeling agent, 34.5% w/w of matrix layer) was found to be promising. Dissolution tests revealed that 84.73% of carvedilol was dissolved from the formulation F151 in 8 h along with satisfactory bio adhesion strength (5.71 g). Bioavailability studies of the promising formulation were compared with that of the oral solution.  The percentage relative bioavailability of the buccal tablets was found to be 121.27%. Stability studies, on the promising formulation indicated that there are no significant changes in drug content and in vitro dissolution characteristics (p<0.05). FTIR studies show no evidence of interaction between drug and excipients. It was concluded that mucoadhesive buccal tablets of carvedilol with controlled unidirectional drug release along with satisfactory bioadhesion strength and with sufficient residence time can be successfully developed by direct compression method.