Formulation and In-vitro Evaluation of Bilayered Buccal Tablets of Carvedilol

Abstract:

Carvedilol was formulated as a bilayered buccal tablet in order to avoid the first-pass effect and decrease the drug loss using different polymers and excipients. Eight formulations were made using different ratio of carbopol 934P and HPMC K4M.The formulations were tested for in vitro drug release, in vitro bioadhesion, moisture absorption and in vitro drug permeation through porcine buccal mucosa. The dissolution of Carvedilol from all the prepared tablets into phosphate buffer (pH 6.8) was controlled and followed by non-fickian release mechanism. Dissolution studies of the tablets of optimized batch containing 5% Carbopol 934P/65% HPMC K4M/30% lactose showed 82.7 % release of drug in 6 h. The mucoadhesive strength and residence time of the optimized batch are 17.93 g and 9.45 h respectively. The swelling index and microenvironment pH of the optimized batch after 6 h are 77.54 and 6.76 respectively. Procured sample of carvedilol was tested for its identification by taking FTIR of pure drug. Drug excipient compatibility was done at 30°C ,65% ± 5%RH, and 40°C 75% ± 5%RH using open and closed vial for four weeks and observed for physical changes. Result does not show any physical changes to mixture after 4 weeks. The results indicate that suitable bioadhesive bilayered buccal tablets with desired permeability using 5-6% Carbopol 934P,65-68%HPMC K4M and 30% Lactose.

Key words: Buccoadhesive tablets, Carvedilol, Mucoadhesion, Carbopol 934P, Polymer