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How are drugs classified by chemical structure, therapeutic use, and mechanism of action?
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Docking of the anticancer drug Gleevec (imatinib) in the abl domain of the bcr-abl tyrosine kinase. Abnormalities in bcr-abl stimulate the continuous proliferation of bone marrow stem cells, causing an increase in myelogenous cells (granulocytes and macrophages) in the body and leading to chronic myelogenous leukemia (CML).
Drugs are generally classified based on their therapeutic use, chemical structure, or mechanism of action. Because these systems often overlap, a single drug may belong to multiple categories, which helps physicians identify alternatives when a patient experiences an adverse reaction.1
Classification Systems
- Therapeutic Use: Drugs are frequently grouped by the disease, tissue, or organ system they target. This approach focuses on the clinical purpose of the medication.12
- Chemical Structure: Categorizing drugs by their molecular makeup facilitates the development of safer and more effective medicines. The structure-activity relationship describes how a drug's specific chemical configuration dictates its biological effect.13
- Mechanism of Action: This classification describes how a drug interacts with the body, often involving receptors—protein molecules that respond to chemical messengers. Drugs are often classified as agonists (which activate receptors) or antagonists (which block them).3
These systems are essential for understanding drug potency and safety, including the therapeutic index, which measures the margin between a beneficial dose and a toxic one.45