CBP is accompanied by profound physiologic changes that may alter pharmacokinetics of many drugs. Drug distribution can be affected by changes in blood flow, hemodilution, and a decrease in protein binding. A reduction in drug elimination is secondary to impairment of hepatic and renal clearance resulting from decreased perfusion and hypothermia. While no single anesthetic technique has been shown to be superior for cardiac surgery, the choice of agent is more often based on cardiovascular side effects than on the need for anesthesia and analgesia. All too often the changes in pharmacokinetic behaviour of drugs imposed by CPB are ignored. These changes become clinically apparent in the postoperative period with patients remaining obtunded and requiring ventilatory support for a protracted period of time, some would argue, unnecessarily.