In this work, we present an ultrasonically powered implantable potentiostat with bidirectional communication for programmable electrochemically controlled drug delivery. The system consists of piezoelectric transducers for wireless power and data, a 180 nm CMOS integrated circuit, and a custom drug delivery module containing drug-loaded electroresponsive nanoparticles. The chip includes power and downlink data recovery circuits for simultaneous power and data transfer up to 50 kbps, a programmable wide-range potentiostat, and a 125 kbps data transmitter. Wirelessly powered and controlled fluorescein release is used to demonstrate the drug delivery system.