Characterization of polyvinylalcohol microspheres of diclofenac sodium: application of statistical design

Microspheres of polyvinylalcohol (PVA) containing diclofenac sodium were prepared by an emulsion-chemical cross-linking method. A statistical design was used to study the variables that affect the preparation of microspheres and to study the release profile of diclofenac from the microspheres. To account for the drug content, a mass balance study of the process was performed. A high concentration of polyvinylalcohol, a high stirring speed, and a low level of glutaraldehyde were found to be important to obtain spherical and discrete microspheres. The concentration of polyvinylalcohol and the amount of heavy liquid paraffin were found to be critical factors in influencing the t50 value. Almost 98% of the total diclofenac sodium added was accounted for in mass balance studies.