Preparation and in vitro evaluation of mucoadhesive chitosan microspheres of amlodipine besylate for nasal administration

Mucoadhesive chitosan microspheres of amlodipine besylate were prepared for nasal administration with the aim of avoiding the first pass effect. A series of batches of microspheres were prepared by simple emulsification crosslinking method to optimize parameters like external phase (mixture of heavy and light liquid paraffin in the ratio of 1:1), stirring rate (1200 rpm), dioctyl sodium sulfosuccinate concentration (0.2% w/v), Chitosan:drug ratio (2:1), volume of crosslinking agent (glutaraldehyde, 1 ml) and time of crosslinking (3 h). The microspheres were evaluated for physical characteristics such as particle size, particle shape and surface morphology by scanning electron microscopy, drug entrapment efficiency, in vitro mucoadhesion, and in vitro drug release characteristics. The microspheres had a mean particle size of 36.47 + 3.39 mm, suitable for nasal administration. Electron microscopy revealed that microspheres were spherical with nearly smooth surface morphology. Application of in vitro drug release data to various kinetic equations indicated matrix diffusion controlled drug release from chitosan microspheres.