Patients admitted to the intensive care unit (ICU) may exhibit multiple organ dysfunctions and usually require treatment with a wide range of drugs such as sedatives, analgesics, neuromuscular blockers, and antimicrobials . Recommendations for the dosing regimens in ICU patients are often extrapolated from clinical trials in healthy volunteers or non-ICU patients. This extrapolation assumes similar drug behavior (pharmacokinetics and pharmacodynamics) among ICU and other patients or healthy volunteers. However, it is well described that many drugs used in critically ill patients may have alterations of the pharmacokinetic and pharmacodynamic properties due to pathophysiological changes or drug interactions [1-4]. These changes may occur even within a single patient at varying stages of their illness and, therefore, critically ill patients offer unique challenges in drug dosing.