Formulation and evaluation of sustained release microspheres of rosin containing aceclofenac

Aceclofenac was microencapsulated using rosin by o/w emulsion solvent evaporation technique. The effect of three formulation variables including the drug: polymer ratio, emulsifier (polyvinyl alcohol) concentration and organic solvent (dichloromethane) volume were examined. The prepared batches were characterized for microspheres particle size distribution, encapsulation efficiency and in vitro release behavior. The study reveals that drug: polymer ratio had a considerable effect on the entrapment efficiency, however particle size distribution of microspheres was more dependent on the volume of dichloromethane and polyvinyl alcohol concentration rather than on the drug: polymer ratio. Drug, polymer concentrations were varied to obtain optimum release profile for sustaining the action of the drug.