ABSTRACT
Pharmacodynamics is the study of the relationship between the drug concentration at the site of action and the pharmacological response (biochemical and physiologic effects). According to occupancy theory, originated by Clark (1933; 1937), the drug effect is a function of the following processes: binding of the drug to the receptor, drug-induced activation (inhibition) of the receptor and propagation of this initial receptor activation (inhibition) into the observed pharmacological effect, where the intensity of the pharmacological effect is proportional to the number of receptor sites occupied by the drug. From Chapter 10, we learned that the interaction of a drug molecule with a receptor causes a chain of reactions (events) that could lead to desirable pharmacological effects or undesirable side effects. Therefore, the relationship between pharmacokinetics and pharmacodynamics is a focus of pharmacodynamics. In Chapter 11, we studied the relationship between dose regimen and plasma drug concentration (PK); in this chapter, we study the drug concentration or, more accurately, the time course of the concentration in relation to pharmacological (positive or negative) re-
in therapeutic window and yield the desired therapeutic or pharmacological response.
