Felodipine is a vasoselective calcium channel antagonist of the dihydropyridine class used in the management of hypertension, with a bioavailability of 15% due to first pass metabolism. We, therefore, aimed to develop a bilayer buccoadhesive tablet of felodipine to avoid presystemic metabolism. Permeation of the drug across the buccal mucosa along with the maximum unidirectional release and full erosion of the tablet in 3h was the objective. From the nine formulations tried, batch F9 containing xanthan gum and Hydroxy Propyl Methyl Cellulose K4M (HPMC K4M) in 2:1 ratio gave the good results for hardness. There was no variation in thickness and weight of tablet. Also tablets passed the friability test. The swelling index, in vitro residence time and in vitro bioadhesion force was found to be 70%, 187±0.029 min and 410±0.02 dyne/cm2 respectively. F9 formulation showed the Matrix (Higuchi) model. According to Matrix (Higuchi) model, the drug release from insoluble matrix is directly proportional to square root of time and is based on fickian diffusion. It reveals that the mechanism of drug release is predominantly diffusion with relatively minor contribution of polymer as well. The overall rate of drug release at 3 h increased with increasing amount of permeation enhancer and polymer (xanthan gum) and maximum release of 98% was obtained.
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