Lacidipine encapsulated gastroretentive microspheres prepared by chemical denaturation for pylorospasm

The purpose of this research work was to formulate and systematically evaluate in vitro performance of mucoadhesive microspheres of lacidipine for treatment of pylorospasm. Lacidipine microspheres containing chitosan were prepared by chemical denaturation using glutaraldehyde as a cross-linking agent. The microspheres were evaluated for physical characteristics such as particle size, particle shape and surface morphology by scanning electron microscopy, drug entrapment efficiency and in vitro mucoadhesion. Results of preliminary trials indicated that the polymer concentration, cross-linking agent and stirring speed had a noticeable effect on size and surface morphology. A central composite design was employed to study the effect of independent variables, polymer concentration (X(1)), volume of glutaraldehyde (X(2)), stirring speed (X(3)) and cross-linking time (X(4)) on dependent variables, drug entrapment efficiency and percentage mucoadhesion. The entrapment efficiency varied from 14-40.82% depending upon the polymer concentration, volume of cross-linker and stirring speed. All batches of microspheres exhibited good mucoadhesive property (73-83%) in the in vitro wash-off test. It was observed that polymer concentration and glutaraldehyde volume had a more significant effect on the dependent variables. Maximum entrapment (36.53%) and mucoadhesion (81.33%) was predicted at 3.5% chitosan, 3 ml glutaraldehyde, 3000 rpm stirring speed and 75 min cross-linking time under optimized process condition. The selected formulation showed controlled release for more than 6 h. The release followed Higuchi kinetics via a Fickian diffusion.