Abstract: A composition for controlled delivery of at least one active substance into an aqueous medium by erosion at a preprogrammed rate of at least one surface of the composition, comprising the active substance, the matrix being erodible in the aqueous medium in which the composition is to be used, and a coating having at least one opening exposing at least one surface of said matrix, the coating comprising a first cellulose derivative which has thermoplastic properties and which is substantially insoluble in the aqueous medium in which the composition is to be used, and at least one of a second cellulose derivative which is soluble or dispersible in water, a plasticizer, and a filler. The coating is a coating which crumbles and/or erodes upon exposure to the aqueous medium such as a body fluid. The first cellulose derivative may be, e.g., ethycellulose, cellulose acetate, cellulose propionate or cellulose nitrate, and the second cellulose derivative may be, e.g.

Abstract: Articles for the controlled delivery of an active substance into an aqueous phase by erosion of surfaces of the articles at a substantially constant and pH-independent rate, the articles comprising a matrix of crystalline polyethylene glycol polymer and a non-ionic emulsifier having an HLB value in the range of from about 4 to about 16 dispersed in the matrix in an amount of between about 2% and 50% by weight of the crystalline polyethylene glycol polymer and the emulsifier, the emulsifier having at least one domain which enables the emulsifier to become emulsified in the melted crystalline polyethylene glycol polymer and being selected from the group consisting of a fatty acid ester and a fatty alcohol ether, the active substance being dispersed in the matrix or located in geometrically well-defined zones within the crystalline PEG phase or dispersed in the emulsifier and, optionally, a filler.