Basic Concepts of Therapeutic Drug Monitoring

Therapeutic Drug Monitoring (TDM) is the process of measuring the concentration of a drug in blood and then correlating it clinically in order to optimize the therapy for the patient. It started in the 1960s and the last three decades have seen enormous spurt in the number of hospitals and laboratories routinely doing it in order to provide greater insights into factors that determine a patient’s response to drug therapy. It is done mainly for drugs with narrow margin of safety, whose therapeutic effects cannot be quantified clinically. Suitable analytical tests like High Performance Liquid Chromatography (HPLC) and Immunoassays are available to detect drug or its metabolites and the results are then interpreted in the context of the condition of the patient. It serves as a useful tool to provide tailor made optimal drug therapy to the patient, thereby maximizing the efficacy and minimizing the side effects.