Pharmacology is the scientific discipline dedicated to the study of drug action and their effects on living systems. It examines the nature, sources, and mechanisms by which chemical substances, known as drugs, interact with biological targets. This field explores pharmacokinetics, which describes the processes of absorption, distribution, metabolism, and excretion of a substance by the body, and pharmacodynamics, which details the biochemical and molecular interactions between the drug and its physiological receptors. By understanding these complex interactions, pharmacological science informs the development of therapeutic agents intended to modify biological functions to prevent, treat, or mitigate disease states.