atc code r atc code r atc code r respiratory 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, qr. national issues of the atc classification may include additional codes not present in this list, which follows the who version. r respiratory system r01 nasal preparations r02 throat preparations r03 drugs for obstructive airway diseases r05 cough and cold preparations r06 antihistamines for systemic use r07 other respiratory system products a b c d g h qi j l m n p r s v