Pharmacology is derived from pharmacos (medicine) and logos (science) words from Greek and it means medication science. The World Health Organization defines medication as "the substance that can be used to change or examine physiological systems or pathological conditions for the benefit of the recipient."
The branch of pharmacology is interested in the discovery of new medicines, making it suitable for use with pre-clinical and clinical trials, monitoring the usage process, the effects of the medicines which are newly developed and used, the side effects and the toxic effects of the medicines, the determination of racial and individual differences especially in terms of enzymes that metabolize medicines, realization of pharmacogenetics, pharmacogenomics and pharmacoepidemiological evaluations, determination of drug-drug and drug-nutrient interactions, application of principles of rational drug use, investigation of bioequivalence of drugs bearing the same active substance. It examines the interaction of drugs with biological systems, it searches for answers of "What does the medication do to the body?" "What does the body do to the drug?“ questions.
Thus, by considering the pharmacoeconomic principles and rational drug use approach, it determines the most appropriate medication required for the diagnosis, treatment and prevention of diseases.