Pharmacology is a branch of 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 molecule which exerts a biochemical or physiological effect on the cell, tissue, organ, or organism. Pharmacology is the study of drug action. It involves looking at the interaction of chemical substances with the systems in our bodies, as well as identifying ways in which our biological systems affect drugs. Let's break it down further and take a look at what the term encompasses and the differences between pharmacology and toxicology, which are often confused. Pharmacology is the study of how a medicine works, how the body responds to it, and the changes that occur over time. Non-clinical pharmacological studies allow scientists to compare a medicine’s beneficial effects with its negative (toxic) effects. This comparison is important so that a thorough benefit-risk analysis can be made before proceeding to test the medicine in clinical (human) studies. If the medicine does proceed to the clinical phase, data gathered during non-clinical pharmacology and toxicology studies help to determine the dosage of medicine given to volunteers in the first clinical studies (first-in-human).