ABSTRACT
Numerous mathematical, thermodynamic, and biochemical models have been put forth to describe the interaction of drugs with drug receptors. According to occupation theory, a linear relationship exists between occupation (binding) of a receptor molecule and the cellular response produced as a result of that receptor occupation. The most obvious weakness in Clark's occupation theory is an underlying assumption that the response produced in cells is linearly proportional to the fraction of the receptor occupied. An alternative model available to determine the effects produced by drug molecules by binding to the receptors are based on the rates of association and dissociation of drugs to and from the receptors. In intact animals or in humans, the responses to low doses of a drug usually increase in direct proportion to dose. Graphic representation of dose-response data is frequently improved by plotting the drug effect (ordinate) against the logarithm of the dose or concentration.
