Guidelines for ATC classification and DDD assignment ... - WHOCC

Example:N02BA71 - acetylsalicylic acid, combinations with psycholeptics (productscontaining other substances in addition to a psycholeptic are also classified here.)Some of the combination products containing psycholeptics have been classified ata separate third or fourth level (e.g. A03C - Antispasmodics in combination withpsycholeptics).There are some exceptions to the main rules and these are explained in theguidelines.Separate ATC 3rd or 4th levels have been assigned for some importantcombinations, e.g. beta blocking agents and diuretics.It may be difficult to decide where a certain combination should be classified. Themain therapeutic use decides the classification. A medicinal product containing ananalgesic and a tranquillizer, and used primarily to ease pain, should be classifiedas an analgesic. Likewise, combinations of analgesics and antispasmodics will beclassified in A03 Drugs for functional gastrointestinal disorders if theantispasmodic effect of the product is considered most important. Similar examplesare described in detail in the guidelines for the relevant drug groups.In some ATC groups a ranking is introduced to help in the classification ofcombination products (e.g. combinations of different antihypertensives andcombinations of different analgesics). This ranking shows which drug takesprecedence over others when the classification is decided. This is detailed in theguidelines for the relevant drug groups.D. Principles for changes to ATC classificationAs the drugs available and their uses are continually changing and expanding,regular revisions of the ATC system will always be necessary.PrincipleChanges in the ATC classification should be kept to a minimum. Before alterationsare made, difficulties arising for the users of the ATC system are considered andrelated to the benefits achieved by the alteration.20