The method of tissue-specific delivery of therapeutic agents via a bio-oncotic pump which includes the steps of furnishing an implantable element which is biodegradable in situ within human tissue. Such an element defines a series of respective concentric shells having different therapeutic agents disposed...http://www.google.es/patents/US5326568?utm_source=gb-gplus-sharePatente US5326568 - Method of tissue-specific delivery
