From the therapeutic point of view, it is essential to ensure that drug concentrations remain within the therapeutic window and neither drug failure, nor drug toxicity, occur in the patient. To understand some of the factors related to drug metabolism that can influence the achievement of these aims.
• What are the metabolic or biotransformational processes that can so dramatically influence drug concentrations and therefore drug action?
• How do these processes sense the presence of the drugs and then remove these apparently chemically stable entities from the body so effectively?
• What happens when these processes are inhibited by other drugs, dietary agents and toxins?
• What is the effect of illness, genetic profile and other patient circumstances on the operation of these processes?
• How can these processes of removal of a drug lead to toxicity?
• What were these processes originally designed to achieve and what is their endogenous function?
The next topic considers the last point and illustrates that in a subject usually termed ‘drug metabolism’, modern drugs are newcomers to an ancient, complex and highly adaptable system that has evolved to protect living organisms, to control instruction molecules and carry out many physiological tasks.
