n the Anatomical Therapeutic Chemical (ATC) classification, drugs are: divided into groups according to which organ or organ system they affect and their chemical, according to its pharmacological and therapeutic properties.
In the ATC system, drugs are grouped into five different levels. Medicines are divided into 14 main categories (Level 1) and up to four levels. Of these, Levels 2 and 3 are therapeutic / pharmacological subgroups, level 4 indicates either pharmacological, chemical or therapeutic group, to which the drug belongs and level 5 of a single chemical substance or combination product combination. In the second, third and fourth levels, pharmacological subgroups are used for identification when considered more appropriate than therapeutic or chemical subgroups.