An analgesic drug delivery system is disclosed herein. The system includes a drug demand interface (110), a patient parameter monitoring device (120), a control system (130), and a drug delivery system (140). The drug demand interface (110) obtains a drug demand from a patient. The patient parameter monitoring device (120) measures pain level of the patient. The control system (130) receives input from the patient parameter monitoring device (120) and the drug demand interface (110) and controls the drug delivery based on effectiveness of the drug. The drug delivery system (140) administers the drug in a controlled manner under the control of the control system (130).