Tableting of coated ketoprofen pellets

Ketoprofen pellets were prepared by the method of extrusion-spheronization, and a film coating of guar gum and Eudragit NE was applied to drug cores using pan technology. In an attempt to design a tablet which, on peroral administration, disintegrates rapidly, releasing intact coated pellets which maintain the integrity of both the cores and their release retarding membrane, Avicel PH101, lactose DT and magnesium stearate were used as excipients to prepare tablets comprising ketoprofen pellets or microcapsules. Preliminary experiments were conducted on uncoated pellets to determine the optimum compression force required to prepare tablets of satisfactory mechanical properties and release profiles. Coated pellets containing ketoprofen were used to investigate the influence of excipients levels. In an attempt to minimize problems associated with blending and segregation of microcapsules and excipients, placebo spheres of Avicel PH101 and lactose DT were produced by the method of extrusion-spheronization. The use of placebo spheres produced tablets with improved drug content uniformity and disintegration time. The tensile strength of such compacts was enhanced by excluding magnesium stearate from the mixes without significant problems of sticking or picking. The use of placebo pellets resulted in significant damage to drug microcapsules, which was attributed to the higher hardness and density of the excipients pellets. The role of membrane coating in protecting the drug core during compression was also evaluated.