title: Formation of water-insoluble gel in dry-coated tablets for the controlled release of theophylline.
abstract: Sodium alginate (ALNa) of a natural polysaccharide is known to form a water-insoluble gel when combined with a bivalent metal. In this study, we prepared tablets containing ALNa and calcium gluconate (GLCa) as a bivalent metal, and studied the application of the water-insoluble gel involving the controlled release of a test drug by permeation of water. Dry-coated tablets containing theophylline (TP) as a model drug, ALNa and GLCa were prepared by the dry power compression method. The controlled release of TP was evaluated by the dissolution test according to JP XIII. The release rate was extremely high for the tablets which contained only TP and GLCa. A zero order or sigmoidal release profile was observed for the tablets that contained only TP and ALNa. On the other hand, the lowest dissolution rate and a sigmoidal release profile were observed for the tablet containing TP and GLCa in its core and ALNa in its outer phase. These results suggest that dry-coated tablets containing ALNa and GLCa and prepared by the direct powder compression method would be useful for the controlled release of drugs.
authors.affiliation: Pharmaceutical Laboratories, Kissei Pharmaceutical Co., Ltd., Nagano, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kaneko
authors.forename: K
authors.initials: K
authors.lastname: Kanada
authors.forename: M
authors.initials: M
authors.lastname: Miyagi
authors.forename: N
authors.initials: N
authors.lastname: Saito
authors.forename: T
authors.initials: T
authors.lastname: Ozeki
authors.forename: H
authors.initials: H
authors.lastname: Yuasa
authors.forename: Y
authors.initials: Y
authors.lastname: Kanaya
mesh_terms: D000464:Alginates / Q000737:chemistry; D001993:Bronchodilator Agents / Q000737:chemistry*; D002125:Calcium Gluconate / Q000737:chemistry; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D005782:Gels; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D012995:Solubility; D013607:Tablets; D013806:Theophylline / Q000737:chemistry*
chemical_list: D000464:Alginates; D001993:Bronchodilator Agents; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D005782:Gels; D006603:Hexuronic Acids; D013607:Tablets; D020723:Glucuronic Acid; D013806:Theophylline; D002125:Calcium Gluconate