A drug delivery system uses an electrically sensitive polymer to store a drug and applies an electric field onto the electrically sensitive polymer for quantitatively and temporally controlled drug delivery. In one embodiment, the drug delivery system is part of a cardiac rhythm management (CRM) system that includes an implantable CRM device and an implantable drug delivery device. The implantable CRM device delivers electrical therapies to a heart and controls the implantable drug delivery device by producing the electrical field with controllable amplitude, frequency, and timing.