Drug delivery systems, apparatus and methods to treat erectile dysfunction via an implanted drug infusion pump. The drug delivery system incorporates a passively pressurized drug infusion pump, one or more catheters, one or more microfluidic valves, a microcontroller, and one or more patient input mechanisms to deliver therapeutic solutions to the erectile tissues of a patient. The system in operation is entirely implanted and provides for moderated patient control over dosage via subcutaneously implanted input mechanisms, including in certain embodiments, neural control.