The KEGG DRUG database is a chemical structure-based information resource for all prescription and OTC drugs in Japan including crude drugs and TCM formulas, as well as most prescription drugs in the USA and many prescription drugs from Europe. In addition to chemical structures (or chemical compositions for multi-component drugs) and therapeutic efficacy of about 9000 drugs (as of September 2009), different drug classification systems are maintained as part of the KEGG BRITE functional hierarchies. Some are based on the established classification systems to which KEGG DRUG entries are assigned, including the ATC (Anatomical Therapeutic Chemical) classification by WHO, therapeutic category of prescription drugs in Japan and classification of OTC drugs in Japan. There are additional classification systems developed by KEGG, including those for crude drugs and TCM formulas.
