ABSTRACT
The critically ill patient presents the intensivist with the challenge of determining appro-
priate and effective pharmacotherapy. The combination of hemodynamic compromise,
organ dysfunction, fluid and electrolyte imbalances, and central nervous system (CNS)
dysfunction may profoundly affect the efficacy and safety of commonly used drugs.
Even slight changes in pharmacokinetics and pharmacodynamics can produce unexpected
responses to pharmaceutical agents in the critically ill patient. Medications routinely used
outside the intensive care unit (ICU) and considered to have a wide margin between thera-
peutic and toxic effects may have a much narrower therapeutic window in the ICU. Some
pharmacological effects may be seen with lower doses, while other pharmacological
effects may be blunted in the critically ill patient, despite the use of the recommended
doses. Clearly, medication use in the ICU requires careful consideration before prescribing
and subsequent close monitoring of the patient to achieve intended therapeutic effects and
avoid potential risks. Another important consideration in the pursuit of optimal medication
use in the ICU is the potential of drugs to interact with each other.
