A biodegradable delivery device is disclosed that is implanted into patients to provide an extended release of one or more active pharmaceuticals for a therapeutic purpose. The delivery device comprises of: 1) an outer sheath that is composed of an inert biodegradable material that prevents the direct interactions of the core(s) with patient tissues and also facilitates the homogenous access of solvent to the surface area of the core to enable predictable core ingredient dissolution, depletion and safe and effective concentrations. 2) A Primary Core comprising one or more active ingredients plus excipients, including markers, that biodegrades and elutes all its ingredients before the sheath degrades. 3) A Secondary Core at the geometric center of the Primary core comprising a marker (including an active pharmacological or inactive ingredient that can be detected by bioanalysis, or a radio-opaque marker) that can signal when the secondary core is exposed, and excipients, which biodegrades and elutes its ingredients. 4) All elements have a marker excipient that renders the device observable remotely, including by x-ray detecting barium sulfate. The Secondary Core has a marker signal that can be distinguished from the Primary Core and Outer sheath.
