Preparation of diclofenac sodium-chitosan microspheres and their matrix tablets by spray drying and pelletization techniques

Abstract

Diclofenac sodium (DS) controlled release microspheres were prepared by spray drying using two different viscosity grades of chitosan. Propylene glycol (PG) and glycerin were chosen for improving the properties of the microcapsules. Extrusion spheronization technique was also used to prepare matrix pellets of DS. The IR spectra revealed no interaction between drug polmers and plasticizers. The lower intensity with higher baseline of X-ray diffractograms and the shifts in exothermic and endothermic peaks of DSC thermograms of the obtained microspheres indicated microsperes indicated an occurrence of amorphous form or other polymorphs. The physicochemical properties of spray dried powders depended on the type and amount of polymers and plasticizers. The complete microcapsules were produced by proper amount of the polymer used with the aid of plasticizer, but no formulation had capability to present satisfactory drug release. Compression of spray dried powders into powders into matrix tablets was very effective for delayed release system. The best formulation achieved about 60% drug released at the 24th hour. The release characteristic was increased with an decrease in the amount of polymers and an increase in amount of plasticizers, while the polymers exhibited stronger effect than plasticizers. PG tended to increase the drug release, whereas glycerin played the opposite role. Study on pelletization suggested that pellets containing microcrystalline cellulose and microcrystalline cellulose with lactose could be produced. Parameters affected the physicochemical properties and dissolution chatacteristics were type and amount of pelletization conditions showed very weak influence. The release characteristics of DS from all formulations were dependent on environmental pH. The efficiency in delay drug released from spray dried powders, matrix tablets and matrix pellets were different and incomparable.