Preliminary Investigations for Process Optimization of Spray Dried Chitosan Microspheres of Felodipine.

Abstract

Spray drying technique for formulation of microparticles compared to conventional methods is proved successful in pharmaceutical research due to unique features of rapid process, reproducibility, comfortable scale up and desired end product properties. The objective of the present investigation is to study the effect of various process parameters for formulation of polymeric microparticles by spray drying technique. Felodipine, a 1,4-dihydropyridine- derivative calcium channel blocking agent, is widely used for the treatment of hypertension, was taken as model drug. Polymeric concentration, drying chamber temperature, feed rate of solution into drying chamber and aspiration rate were optimized for felodipine loaded chitosan microparticles. The batches were formulated by varying each parameter at a time and keeping all other parameter constant. The microparticles were evaluated for % yield, entrapment efficiency, average particle size, particle size distribution, particle shape, true density, flow property and in-vitro drug release. The microparticles with higher polymeric concentration retarded burst release of drug. The higher temperature of drying chamber reduces the entrapment efficiency and increases the average particle size; however microparticles had irregular particle shape. Faster feeding of solution caused sticking of polymeric solutions on the wall leading to poor yield, which may be due to insufficient drying time. The lower aspiration rate also caused sticking of feed on wall and higher aspiration caused conveying of particles to fine collector filter bag leading to poor yield, hence the optimum aspiration is pre-requisite for good yield. The results of % yield and entrapment efficiency were found varied in different batches, which indicates that selected process parameters is significantly affecting the process. At the end, it may be concluded that the microparticles with desirable physical characteristics and drug release may be formulated by systemically optimizing critical process parameters of spray drying technique.