Pharmacology
Explanation: is a branch of medicine and pharmaceutical sciences which is concerned with the study of drug or medication action,where a drug can be broadly or narrowly defined as any man-made, natural, or endogenous (from within the body) molecule which exerts a biochemical or physiological effect on the cell, tissue, organ, or organism (sometimes the word pharmacon is used as a term to encompass these endogenous and exogenous bioactive species).