DEVELOPMENT AND IN-VITRO EVALUATION OF A NOVEL MULTIPARTICULATE MATRIX CONTROLLED-RELEASE FORMULATION OF THEOPHYLLINE

A novel multiparticulate matrix controlled release preparation of theo phylline was formulated and evaluated in-vitro. The preparation which consisted of spherical drug pellets in a size range of 1.18 - 1.70 mm diameter was produced using an extrusion-spheronisation technique. The drug was embedded in a mixture of nonsoluble matrix materials forming the pellets to control the drug release. For this purpose, microcryst alline cellulose (MCC) and its mixture with glyceryl monostearate (GMS ) were evaluated. When microcrystalline cellulose was used alone, the drug release was not sufficiently sustained and was essentially comple te within 6 hours. However, incorporation of glyceryl monostearate sig nificantly retarded the rate of drug release. Moreover, the rate of dr ug release could be readily modified in a predictable manner by varyin g the amount of glyceryl monostearate. The rate of the drug release wa s relatively insensitive to changes in the drug to matrix ratio. Dryin g of the drug pellets at temperatures below the melting point of glyce ryl monostearate (approximately 57 degrees C) has no effect on the rat e of drug release. In addition, the rate of drug release was found to be Stable after storage for 6 months and was essentially independent o f pH and agitation rate.