A drug class is a group of medications that share something important in common: they treat the same condition, work in the body the same way, or have a similar chemical makeup. A drug class is typically defined by a prototype drug, the most important, and typically the first developed drug within the class, used as a reference for comparison. Drugs, substances, and certain chemicals used to make drugs are classified into five (5) distinct categories or schedules depending upon the drug’s acceptable medical use and the drug’s abuse or dependency potential. Here is a list of the different drug classifications and what they mean. These drugs are known to have a high risk of abuse and addiction, along with no accepted medicinal use. For that reason, healthcare providers cannot prescribe them to patients. Examples of Schedule I drugs include: Search or browse a complete list of drugs marketed in the U.S. organized by class or chemical type. Learn about drug classifications with clear explanations and examples. Understand how drugs are grouped by use, action, structure, and legal status. Drug classifications refer to the Drug Enforcement Administration's scheduling of drugs based on their abuse potential, medical use, and other criteria. Learn what the different schedules of drugs are and get examples of drugs in each schedule.