V. Ravi Krishna, Y. Madhusudhan Rao, P.Chinna Reddy ,K. Sujatha
The objective of this study was to develop effective mucoadhesive buccal bilayered tablets of a drug containing bioadhesive layer and drug free backing layer, expected to release the drug in unidirection for extended period of time. Tablets of Furosemide were prepared by direct compression method using bioadhesive polymers like Carbopol 941NF, 971P, Methocel K4M, Methocel K15M and combination of NaCMC, Carbopol 971P in different ratios with backing layer of Cyanoacrylate adhesive tape. Buccal tablets were evaluated by different methods for parameters such as thickness, hardness, weight uniformity, content uniformity, swelling index, surface pH, ex vivo bioadhesive strength, ex vivo residence time, in vitro drug release, ex vivo drug permeation, stability studies in human saliva, in vivo mucoadhesive performance studies. Bioadhesion strength was increased with increase in the concentration of carbopol and HPMC formulations. The tablets were evaluated for in vitro release in pH 6.6 phosphate buffer for 6 hr in standard dissolution apparatus. Burst release was observed in formulation with carbomers when compared to HPMC grades, but in combination (i.e. NaCMC with Carbopol- 971P) improves the release and permeation rate when compared with carbopol-971P individually. In order to determine the mode of release, the data was subjected to Zero order, first order, Higuchi, Korsmeyer and Peppas diffusion model. The optimized formula (Fa2) followed fickian release mechanism with Peppas diffusion kinetics. Drug, HPMCK4M in the ratio of 1:1 could be used to design effective and stable buccoadhesive tablets of Furosemide
