ATCcode

ATC code refers to the Anatomical Therapeutic Chemical Classification System code, a globally used framework for classifying active substances and drug products. It is maintained by the World Health Organization’s Collaborating Centre for Drug Statistics Methodology and is widely employed in drug utilization research, health statistics, and pharmacoeconomic analyses. The system provides a standardized language to describe medications across countries and over time.

The ATC classification uses a five-level hierarchical structure. The first level designates the anatomical main group, reflecting the body system affected by the drug. The second level specifies the therapeutic subgroup, indicating the condition or use. The third level denotes the pharmacological subgroup, describing the drug’s mechanism of action. The fourth level identifies the chemical subgroup, and the fifth level designates the chemical substance itself. Each level adds precision, allowing researchers to group drugs at varying levels of specificity.

Codes are alphanumeric and arranged so that broader categories share a common prefix with more specific codes. The ATC system encompasses individual substances as well as fixed-dose combinations and formulations. While the code points to the substance, it does not replace information such as brand names or indications, which are recorded separately in medical records and regulatory documents.

Applications of ATC codes include international comparisons of drug utilization, pharmacovigilance, and health services research. The ATC/DDD Index, which links codes to defined daily doses, is updated annually to reflect new therapies and evolving clinical practice, supporting standardized reporting and analysis across health systems.