Pharmacokinetics and pharmacodynamics of antimicrobial drugs in intensive care unit patients.

Inappropriate use of antimicrobial drugs is responsible for therapeutic failures, increased mortality rates, and the emergence of resistance. Antimicrobial activity is determined by intrinsic pharmacokinetics/pharmacodynamics concepts. In critically ill patients, an inappropriate dosing regimen can be caused by the inability of an antimicrobial drug to reach adequate concentrations at the infection site owing to alterations in the drug's pharmacokinetics caused by pathophysiological changes. Understanding these concepts and changes in PK-PD parameters that occur in intensive care unit patients is crucial for the optimization of antimicrobial therapy in these patients.