Sustained release capsule and method for preparing the same

Abstract

A sustained release capsule in which an outer surface of a hard capsule mainly composed of gelatin and containing a physiologically active substance is uniformly covered with a film material comprising a natural polysaccharide/polyhydric alcohol composition which is prepared by uniformly kneading at least one natural polysaccharide selected from the group consisting of carrageenan, alginic acid, salts of alginic acid, derivatives of alginic acid, agar, locust bean gum, guar gum, pectin, amylopectin, xanthane gum, glucomannan, chitin and pullulan in at least one system selected from the group consisting of polyhydric alcohols, sugar alcohols, monosaccharides, disaccharides, trisaccharides and oligosaccharides. A capsule formed merely of the natural polysaccharide/polyhydric alcohol composition swells and is permeated by water. It is poor in shape-retaining properties, failing to retain its shape in the stomach, although it is nondigestive. However, the gelatin capsule covered with this composition prevents digestion of gelatin, can be conveyed to the small intestine without deactivation of the physiologically active substance contained therein, and can gradually release the contents in the intestine at a speed according to its purpose, so that it is useful for the effective utilization of the physiologically active substance.