atc code a13 atc code a13 atc code a13 tonics is a therapeutic subgroup 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. subgroup a13 is part of the anatomical group a alimentary tract and metabolism. atc codes a alimentary tract and metabolism a01 stomatological preparations a02 drugs for acid related disorders a03 drugs for functional gastrointestinal disorders a04 antiemetics and antinauseants a05 bile and liver therapy a06 drugs for constipation a07 antidiarrheals, intestinal anti-inflammatory/anti-infective agents a08 antiobesity preparations, excluding diet products a09 digestives, including enzymes a10 drugs used in diabetes a11 vitamins a12 mineral supplements a13 tonics a14 anabolic agents for systemic use a15 appetite stimulants a16 other alimentary tract and metabolism products a b c d g h qi j l m n p r s v codes for veterinary use (atcvet codes) can be created by placing the letter q in front of the human atc code: for example, qa13. national issues of the atc classification may include additional codes not present in this list, which follows the who version. a13a tonics this group is empty.