Abstract: A gastric remaining preparation having a configuration entirely different from that of the conventional ones. It comprises a swollen molding having a mesh-like cross-section and an apparent density of less than 1, containing an acid-resistant polymer compound as a predominant component as well as at least an auxiliary blowing agent and a drug substance. The molding can be produced by using a multi-screw extruder.

Abstract: This invention has for its object to provide a method of inducing a transition in crystalline state of a crystallizable medicinal substance with great ease and improved efficiency and uniformity on a high production scale. According to the invention, an extruder is used for inducing a transition from one crystalline state (.DELTA.) to another crystalline state in a crystallizable medicinal substance.

Abstract: A method of producing a wax matrix for controlled release of a pharmaceutically active ingredient is provided. The method includes the steps of feeding a wax and a pharmaceutically active ingredient into a multi-screw extruder and thoroughly mixing the wax with the pharmaceutically active ingredient using the multi-screw extruder to form a wax matrix. The wax matrix thus produced provides a controlled release of the active ingredient.

Abstract: A process for producing a pharmaceutical composition is disclosed. In the process, 1 part by weight of a physiologically inert powdery additive, 0.001-1 part by weight of a macromolecular additive per part by weight of said insert powdery additive, and at least one drug substance are used as ingredients and processed en bloc by means of a multi-screw extruder. The drug substance used in the process can be selected from the following group: subliminable drug, volatile drug, drug hydrolyzable in the presence of water, drug which develops whiskers, and hygroscopic or deliquescent drug. The process confers increased physicochemical stability to the pharmaceutical composition and the drug substance contained therein.