Lilia Malkin, BSc
Throughout the centuries, people have turned to medicinal substances to improve their health and quality of life. Today, medi-cations continue to be invaluable partners in humanity's war against disease. However, each person has a unique response to his or her medication(s). The differences among patients' reactions to pharmaceutical therapy can be at least partially explained by the inter-individual variation in drug metabolism. As biotechnology continues to make progress, the genetic foundation for illness and the consequent response to treatment is becoming increasingly apparent.1,2 The basis for patient-to-patient variability in the effects of pharmaceutical agents has thus far been attributed predominantly to the drug-metabolizing capacity of the liver.1 Accordingly, this article will focus on the hepatic biotransformation enzymes and the contribution of genetic polymorphism to individuals' thera-peutic responses and to treatment-related complications. It should be noted that tissue receptors and transporter proteins are also often subject to polymorphic variations, contributing to the variable response to medications and toxins; a discussion of this topic is, however, beyond the scope of this paper.
Hepatic Drug Metabolism Enzymes: An Overview
The metabolism and elimination of pharmaceutical agents may occur at several sites in the human body, including the liver, kidneys, gastrointestinal (GI) tract, lungs, and skin.