<P> Pharmacology is the branch of biology concerned with the study of drug action, where a drug can be broadly defined as any man - made, natural, or endogenous (from within 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). More specifically, it is the study of the interactions that occur between a living organism and chemicals that affect normal or abnormal biochemical function . If substances have medicinal properties, they are considered pharmaceuticals . </P> <P> The field encompasses drug composition and properties, synthesis and drug design, molecular and cellular mechanisms, organ / systems mechanisms, signal transduction / cellular communication, molecular diagnostics, interactions, toxicology, chemical biology, therapy, and medical applications and antipathogenic capabilities . The two main areas of pharmacology are pharmacodynamics and pharmacokinetics . Pharmacodynamics studies the effects of a drug on biological systems, and Pharmacokinetics studies the effects of biological systems on a drug . In broad terms, pharmacodynamics discusses the chemicals with biological receptors, and pharmacokinetics discusses the absorption, distribution, metabolism, and excretion (ADME) of chemicals from the biological systems . Pharmacology is not synonymous with pharmacy and the two terms are frequently confused . Pharmacology, a biomedical science, deals with the research, discovery, and characterization of chemicals which show biological effects and the elucidation of cellular and organismal function in relation to these chemicals . In contrast, pharmacy, a health services profession, is concerned with application of the principles learned from pharmacology in its clinical settings; whether it be in a dispensing or clinical care role . In either field, the primary contrast between the two are their distinctions between direct - patient care, for pharmacy practice, and the science - oriented research field, driven by pharmacology . </P>

The study of the effects of drugs on mind and behavior is called