Pharmacokinetics and Pharmacodynamics are the two broad divisions of Pharmacology which is a broad field involve the interactions between drugs and body. Pharmacokinetics is the study of interval or time taken in drug absorption, distribution, metabolism and excretion over time. In another way it is the way or route of administration of specific drug with specified amount, frequency to the living organisms. It also refers to the movement of the drug in and out of the body in its time of course. It is also called as clinical pharmacokinetics. The main steps involved are:

Pharmacodynamics is the study of drug concentration at the drug site of action and their effects in the given time course and intensity of therapeutic and adverse effects in other words it is the study of how medicine acts on the body including both biochemical and physiological effects of the drug along with the relationship between drug concentration and effect. The effect of the drug is determined by the binding action of drug with receptor.