KEGG DRUG is a comprehensive drug information resource for approved drugs in Japan, USA, and Europe unified based on the chemical structures and/or the chemical components, and associated with target, metabolizing enzyme, and other molecular interaction network information. All the marketed drugs in Japan, not only the prescription drugs but also the OTC drugs, are fully represented in KEGG DRUG and integrated with the package insert information (labels information). These include crude drugs and TCM (Tradictional Chinese Medicine) drugs.

Each KEGG DRUG entry is identified by the D number distinguishing the chemical structure of chemicals or the chemical component of mixtures. It is associated with the following information (see, for example, D01441 or Gleevec for the treatment of chronic myeloid leukemia).

• Generic names (associated with chemical structures, see details below)
• Representative trade names
• Links to FDA approved drug labels information in DailyMed
• Chemical structure, chemical component, peptide/polyketide sequence
• Target molecules in the context of KEGG pathway maps
• Drug metabolizing enzymes and transporters
• Other interacting molecules including genomic biomarkers, CYP inducers/inhibitors, etc.
• Adverse drug-drug interaction data (collected from the Japanese package inserts)
• Text description of activity and efficacy
• Therapeutic category, ATC code, and other drug classification information in BRITE hierarchy
• History of drug development represented as a KEGG DRUG structure map
• Links to outside databases

For representation of efficacy and therapeutic use, different drug classification systems are maintained as part of the KEGG BRITE functional hierarchies. The first group is based on the established classification systems to which KEGG DRUG entries are manually assigned. The classification may be examined with additional information on targets and metabolizing enzymes shown in a separate column.

Category	Classification	Additional info		Remark
Prescription drug	ATC Classification	Target	Enzyme	ATC 2012
	USP drug classification	Target	Enzyme	v5.0
	Therapeutic category of drugs in Japan	Target	Enzyme	JP16
OTC drug (Japan)	Classification of Japanese OTC drugs
	Risk category of Japanese OTC drugs

The second group consists of additional classification systems developed by KEGG.

Category	Classification	Remark
Prescription drug	Target-based classification
	Antiinfectives
	Antineoplastics
Crude drug (Japan)	TCM drugs in Japan	See also: KEGG ENVIRON
	Crude drugs in Japan

Furthermore, the following information is provided.

Category	Information
Prescription drug	Drugs listed in the Japanese Pharmacopoeia
OTC drug	Rx-to-OTC switch list in Japan
	Rx-to-OTC switch list in the USA

Labels information (in Japanese) of all marketed drugs in Japan is provided through the Japanese version of KEGG DRUG.

Many marketed drugs have been developed from lead compounds or existing drugs by introducing chemical structure transformations retaining the core chemical structures. KEGG DRUG structure maps graphically illustrate, in a manner similar to KEGG pathway maps, our knowledge on such drug development. They are in the Drug Development category of the KEGG PATHWAY database.

• KEGG Pathway Maps: Drug Development

The chemical structure of a drug is identified by the standardized generic name, but the names can be different in different countries or organizations. The same structure may be called differently and the same name may mean different structures. To accomodate such differences the generic names are associated with the following codes in parentheses.

• JAN - Japanese Approved Name
• USAN - United States Adopted Name
• NF - National Formulary drug name
• INN - International Nonproprietary Name
• BAN - British Approved Name
• DCF - Dénomination commune française

In addition, drugs listed in the pharmacopoeia are denoted by:

• JP16 - Japanese Pharmacopoeia, 16th edition
• USP - United States Pharmacopeia

which also imply the JAN and USAN names, respectively.

Selected trade names (TNs) are also given in each KEGG DRUG entry. More names may be found from the outside link to DailyMed, which provides FDA approved labels information of marketed drugs.