Controlled release powder and process for its preparation

A controlled release taste-masked powder containing discrete micro-particles for use in edible, pharmaceutical and other controlled release compositions, said powder comprising particles containing theophylline as an active ingredient in intimate admixture with at least two polymers, at least one of which is soluble and at least one of which is water insoluble, in an amount effective to provide a predetermined and controlled release of said active ingredient, each of said particles being in the form of a micromatrix with the active ingredient uniformly distributed throughout the matrix, but not entirely coated by the polymers, said particles having an average size of from 0.1 to 125 .mu.m, being unlikely to be significantly degraded or ground by any chewing action, and wherein said predetermined release of active ingredient is suitable for twice daily administration, wherein said soluble polymer(s) is (are) selected from the group consisting of:

• polyvinyl alcohols, water soluble alkyl celluloses, hydroxyalkyl celluloses, water soluble cellulose esters, polyalkylene glycols, polyvinylpyrrolidone, and polymers thereof, and said water insoluble polymer(s) is (are) selected from the group consisting of water insoluble alkyl celluloses, water insoluble cellulose esters, nitro celluloses, polymers of acrylic and methacrylic acids and esters thereof, polyamide, polycarbonates, polyalkylenes, polyalkyline oxides, polyalkylene terephthalates, polyvinyl ethers, polyvinyl esters, polyvinyl halides, polyglycolides, polysiloxanes, polyurethanes, and co-polymers thereof.