Pitfalls in monitoring therapeutic drugs

Abstract

The first and foremost need for proper therapeutic drug monitoring is an appropriate medical indication. The laboratory's role is to collect and analyze samples. This article describes how these procedures must be carried out. Meticulous attention must be paid to the timing of samples (peak, trough, postdistribution), the reporting of ancillary information (such as time of sampling), and the analytic validity of the chosen method. Limitations of immunoassay procedures for drugs are discussed briefly with the focus on the effects of cross-reacting and interfering substances.