Pharmacology is the science related to the interaction between chemical agents and living systems. Pharmacology can be divided into two main branches - pharmacodynamicsandpharmacokinetics.

1. Pharmacodynamics focuses on what the drug does to the body. It encompasses the study of the biochemical, molecular, and physiological effects of drugs on the body, including the specific mechanisms of drug action. 
2. Pharmacokinetics focuses on what the body does to the drug. It encompasses the study of the absorption, metabolism, distribution, and elimination of a drug.