An implantable drug delivery apparatus for delivering a drug into a bodily fluid in a body cavity of a patient over a period of time, which includes a hollow member that defines at least one lumen for facilitating a unidirectional recirculating flow of a therapeutic fluid through the lumen. The fluid can contain a bodily fluid, such as, for example, perilymph, and a drug. The apparatus also includes a pump, for example a single unidirectional pump, to control the flow rate of the therapeutic fluid through the hollow member, and an interface member in communication with at least one lumen of the hollow member. The device thus allows for the controlled delivery of the therapeutic fluid to a predetermined location in the bodily cavity of the patient, such as, for example, a cochlea of a human ear.