How are pharmaceuticals classified by chemical group and therapeutic use?

Pharmaceuticals are generally classified based on their chemical structure, their pharmacological effect (how they work in the body), and their therapeutic use. Because these systems overlap, a single drug may be categorized in multiple ways, which helps physicians identify alternatives if a patient experiences an adverse reaction.12

Classification by Chemical Group

Chemical classification focuses on the molecular composition of a drug. Understanding a drug's structure is essential for researchers to develop safer and more effective medicines. Examples include:13
* Alkaloids: The first pure pharmaceuticals derived from natural plant sources, such as quinine, cocaine, and morphine.23
* Steroids: Characterized by a specific four-ring molecular structure, these are modified through chemical synthesis or treatment of natural compounds.4
* Other Origins: Drugs may also be derived from animal extracts (e.g., insulin) or manufactured via laboratory synthesis.23

Classification by Therapeutic Use

Therapeutic classification groups drugs according to the disease, tissue, or organ system they treat. This includes categories such as antibiotics for infections, antihypertensives for blood pressure, and analgesics for pain relief. Additionally, controlled substances are classified into five schedules based on their potential for abuse and dependence.15