This document provides an introduction to psychopharmacology, covering general principles like drug classification, mechanisms of action, metabolism and guidelines for use. It discusses the four main drug categories - antipsychotics, mood stabilizers, antidepressants and anxiolytics - and how they are used to treat an expanding range of disorders. Key concepts covered include how drugs are absorbed, distributed, metabolized and excreted from the body. Special considerations for vulnerable patient populations and common adverse effects and their management are also summarized.