Plasma drug concentrations in therapeutics.

The literature describing drugs assay in plasma and its value for optimal therapy for individual patients is expanding rapidly. The present review seeks to clarify the rationale underlying the assay of plasma concentrations of drugs, and it attempts to define principles for judging the likely value of assaying a particular drug. Examples are given of drugs which are being usefully measured in clinical practice. The most commonly used assay techniques are briefly described, and their principal advantages and limitations are indicated.