In vivo, in vitro evaluation of linseed mucilage based buccal mucoadhesive microspheres of venlafaxine

The purpose of the present research work was to extract linseed mucilage, use it as a mucoadhesive agent and to develop mucoadhesive microspheres for buccal delivery with an intention to avoid hepatic first-pass metabolism, by enhancing residence time in the buccal cavity. Linseed mucilage was extracted and used to prepare microspheres with varying concentrations of mucilage from formulation F1-F4 (1-2.5%) by spray-drying technique. The microspheres were evaluated for the yield, particle size, incorporation efficiency, swelling property, in vitro mucoadhesion, in vitro drug release, histological study, and stability. Microspheres were characterized by differential scanning colorimetry, scanning electron microscopy, and X-ray diffraction study. Further, the bioavailability study using the New Zealand rabbits was carried out. Formulation F4 showed the maximum mucoadhesion 89.37 +/- 1.35%, 92.10 +/- 1.37% incorporation efficiency, highest swelling index 0.770 +/- 1.23. F4 showed a marked increase in the bioavailability after buccal administration (51.86 +/- 3.95) as compared to oral route (39.60 +/- 6.16). Also it took less time to reach maximum plasma concentration of 21.38 +/- 1.05 ng/ml as compared to oral solution where it required 180 min to reach maximum plasma concentration of 17.98 +/- 1.14. It is concluded from the results that linseed mucilage can be used in the production of the mucoadhesive microspheres.</.