How to measure pharmacokinetics in critically ill patients?

There is pressing need to better understand pharmacokinetics in critically ill patients. This will aid clinicians in selecting optimal dosing regimens. Pharmacokinetic studies are difficult in this population due to the heterogeneity of the patients and the practical issues of research involving critically ill patients. Therapeutic drug monitoring is routinely performed to guide dosing for aminoglycoside and glycopeptide antibiotics. Expanding its use to other drug classes could provide new therapeutic advantages. Plasma concentration may not always reflect tissue distribution in critically ill patients. Microdialysis is a technique that can be applied in the Intensive Care Unit to measure tissue concentrations and provide further insights to antimicrobial therapy for critically ill patients. Finally, the application of population pharmacokinetic analysis in studies in critically ill patients may identify factors affecting pharmacokinetics and enhance drug dosing regimens for varied patient groups.