Pharmacology is the branch of treatment and biology concerned with the formulation of drug action, where a drug is also commonly defined as any man-made, typical, or endogenous molecule that has a biochemical effect. and/or physiologically on cells, tissues, and organs. or creatures. Specifically, it is the study of the interactions that occur between a living organism and chemical substances that affect normal or abnormal biochemical function. If the substances have medicinal properties, they are considered pharmaceuticals. where a drug is generally defined as any man-made, natural, or endogenous (in vivo) molecule that produces a biochemical or physiological effect on an organism's cells, tissues, or organs. Specifically, it is the study of actions between a living organism and chemical substances that affect normal or abnormal biochemical function. If substances have healing properties, they are called pharmaceuticals. Pharmacology includes drug composition and characterization, drug synthesis and design, molecular and cellular mechanisms, systemic mechanisms, signal transduction, molecular diagnostics, interactions, toxicology, and biology. chemistry, therapy, medical applications, and resistance to pathogens.