Rational approach to therapeutic drug monitoring.

The measurement of drug concentrations in blood samples may provide useful clinical information on the relationship between drug administration and drug efficacy or toxicity. For optimal use of the measurement of plasma drug concentrations in clinical practice, the physician must be familiar with the principles of therapeutic drug monitoring and the data available on interpreting the blood drug levels for the specific drug of interest. This review presents an approach for using therapeutic drug monitoring in the clinical setting and illustrates this approach with several drugs for which therapeutic drug monitoring is commonly applied.