Pharmacodynamics of antiinfective therapy: Taking what we know to the patient's bedside

Applied pharmacokinetics has long been a lifeline of clinical pharmacy serv ices. National surveys during the past decade documented clinical pharmacy services and demonstrated that a substantial rate of growth occurred in cli nical pharmacokinetic consultations and management of drug therapy protocol s. Pharmacodynamic principles of antiinfective agents are rapidly becoming a new paradigm of clinical pharmacy services. beta -Lactams, aminoglycoside s, and fluoroquinolones represent the three classes of antiinfective agents that have made the most progress toward the clinical applications of pharm acodynamics. Pharmacodynamic parameters are being used to select and compar e agents within an antiinfective class (e.g., fluoroquinolones), make modif ications in the dosage (e.g., extended-interval dosing of aminoglycosides) and/or mode of administration (e.g., continuous infusion of beta -lactams), develop in vivo breakpoint determinations, and assess the development of b acterial resistance. In addition, pharmacodynamic parameters have influence d the clinical drug development of new (e.g., linezolid) and older (amoxici llin-clavulanate, fluoroquinolones) antiinfective agents. Further investiga tions are needed to explore the clinician's use of validated prediction met hods and patient-specific pharmacodynamic parameters at the bedside. By lin king pharmacokinetic services with pharmacodynamic principles, the opportun ity for continued progress toward our assessment and decisions for successf ul clinical outcomes is possible with old and new antiinfective agents.