PROCESS FOR PREPARING CONTROLLED-RELEASE PREPARATION

A pharmaceutical controlled release formulation is disclosed which does not substantially disintegrate but gradually releases a physiologically active substance in the gastrointestinal tract and which comprises a granulation product (granules) obtained by adding release controlling agent (e.g. an aqueous suspension of a water insoluble macromolecular substance, an aqueous emulsion thereof, a water containing organic-solvent solution thereof, or water) to a mixture of i) physiologically active substance and ii) carrier substance (e.g. crystalline cellulose) in an amount of at least 50% by weight based on the weight of the product, and granulating the resultant mixture. The active substance containing granules have a high mechanical strength, disperse widely in the gastrointestinal tract when administered, are water permeable but do not substantially disintegrate in the gastrointestinal tract.