ABSTRACT
The assay of serum or plasma for therapeutic drugs is a relative newcomer to routine clinical laboratory operations, starting in the early 1970s (Marks, 1985). Research studies have shown that responses to drugs are more·closely correlated with blood concentration than with dose [a review of this literature has been provided by Burton et al. (1985)]. Clinical experience has demonstrated the importance of individualizing drug therapy because of wide patient-to-patient variation in the parameters of drug absorption, distribution, and elimination as well as in physiological response.
