Anatomical Theraputic Chemical (ACT) Classification

The Anatomical Therapeutic Chemical (ATC) Classification System is a widely used standardized classification system for drugs. It was developed by the World Health Organization (WHO) collaborating with the Center for Drug Statistics Methodology and was first published in 1976. The ATC system is designed to categorize pharmaceutical substances according to their therapeutic, pharmacological, and chemical properties.

The ATC system classifies drugs based on three main characteristics:

• Anatomy: The organ or system on which the drug acts (e.g., the nervous system, the cardiovascular system)
• Therapeutics: The therapeutic effect of the drug (e.g., antibiotics, antidepressants)
• Chemistry: The chemical properties of the drug (e.g., steroids, non-steroidal anti-inflammatory drugs)

The ATC system has a hierarchical structure with five levels of classification:

1. First level: Anatomical main group
2. Second level: Therapeutic subgroup
3. Third level: Pharmacological subgroup
4. Fourth level: Chemical/therapeutic/pharmacological subgroup
5. Fifth level: Chemical substance

First level: Anatomical main group (one letter)

The first level of the ATC code consists of 14 anatomical main groups, which are represented by a single letter:

• A: Alimentary tract and metabolism
• B: Blood and blood-forming organs
• C: Cardiovascular system
• D: Dermatologicals
• G: Genito-urinary system and sex hormones
• H: Systemic hormonal preparations, excluding sex hormones and insulins
• J: Anti-infectives for systemic use
• L: Antineoplastic and immunomodulating agents
• M: Musculoskeletal system
• N: Nervous system
• P: Antiparasitic products, insecticides, and repellents
• R: Respiratory system
• S: Sensory organs
• V: Various

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