• It is defined as, “the study of the actions and effects of drugs at all levels of organisation of living material and of the handling of the drugs by the organism”. It includes following components:
o The biological effects produced by drugs.
o The site(s) at which and mechanism(s) by which the biologic effects are produced.
o The factors which influence safety and effectiveness of drugs.
o Principles and mechanism of drug action.
• In simpler words, pharmacodynamics involves what drug does to the body and how does it do it.