Article for the controlled delivery of an active substance, comprising a hollow space fully enclosed by a wall and filled in full or in part with one or more active substances

An article for the controlled delivery of an active substance, comprising a hollow space fully enclosed by a wall and filled in full or in part with one or more active substances, wherein the wall is comprised of a portion or portions of a first polymeric material that is permeable to the active substance and is degradable and a portion or portions of a second polymeric material that is poorly permeable to the active substance relative to the first polymeric material and is degradable, and wherein there is a transport path for the delivery of the active substance from the hollow space to the surroundings of the article which is a continuous distance leading through the first polymeric material permeable to the active substance, and wherein the first and second polymeric materials are selected from polyesters, polyorthoesters, poly(.alpha.-amino acids), polydepsipeptides, polyanhydrides and polyphosphazenes, co- or block co-polymers derived therefrom and stereo complexes of polymers formed from optically active monomers of these biodegradable polymers.