Pharmacology is the study of how medicine and other things have an effect on living organisms and change how they function. Pharmacology could also be defined as the study of how medicine actually works. Pharmacology is not exactly the same as pharmacy, and a pharmacologist is not exactly the same as a pharmacist. A pharmacologist is a scientist who studies how medicine actually works and usually works in a science lab. A pharmacist is a health care provider who usually works at a pharmacy. However, there is quite a bit of overlap between these two fields. A pharmacist could be considered a type of pharmacologist. While in school, pharmacists do take many classes in pharmacology.

The two main divisions of pharmacology are pharmacodynamics and pharmacokinetics.

Pharmacodynamics:-(Greek: Dynamis—power) What the drug does to the body. This includes physiological and biochemical effects of drugs and their mechanism of action at organ system/subcellular/macromolecular levels.

Pharmacokinetics:-(Greek: Kinesis—movement) What the body does to the drug. This refers to the movement of the drug in and alteration of the drug by the body; includes absorption, distribution, binding/localization/storage, biotransformation, and excretion of the drug, e.g. paracetamol is rapidly and almost completely absorbed orally attaining peak blood levels at 30–60 min; 25% bound to plasma proteins, widely and almost uniformly distributed in the body (volume of distribution ~ 1L/kg); extensively metabolized in the liver, primarily by Glucuronide and sulfate conjugation into inactive metabolites which are excreted in urine; has a plasma half-life (t½) of 2–3 hours and a clearance value of 5 ml/kg/min.