atc code n atc code n atc code n nervous system is a section of the anatomical therapeutic chemical classification system, a system of alphanumeric codes developed by the world health organization (who) for the classification of drugs and other medical products. codes for veterinary use (atcvet codes) can be created by placing the letter q in front of the human atc code: for example, qn. atcvet codes without corresponding human atc codes are cited with the leading q in the following list.national issues of the atc classification may include additional codes not present in this list, which follows the who version. n nervous system n01 anesthetics n02 analgesics n03 antiepileptics n04 anti-parkinson drugs n05 psycholeptics n06 psychoanaleptics n07 other nervous system drugs atcvet only qn51 products for animal euthanasia a b c d g h qi j l m n p r s v