Guidelines for ATC classification and DDD assignment - WHOCC

Example:
N02BA71 - acetylsalicylic acid, combinations with psycholeptics (products
containing other substances in addition to a psycholeptic are also classified here.)
Some of the combination products containing psycholeptics have been classified at
a separate third or fourth level (e.g. A03C - Antispasmodics in combination with
psycholeptics).
There are some exceptions to the main rules and these are explained in the
guidelines.
Separate ATC 3rd or 4th levels have been assigned for some important
combinations, e.g. beta blocking agents and diuretics.
It may be difficult to decide where a certain combination should be classified. The
main therapeutic use decides the classification. A medicinal product containing an
analgesic and a tranquillizer, and used primarily to ease pain, should be classified
as an analgesic. Likewise, a preparation used for functional gastrointestinal
disorders will be classified under A03, Drugs for functional gastrointestinal
disorders, even if it contains small amounts of analgesics and/or psycholeptics.
Similar examples are described in detail in the guidelines for the relevant drug
groups.
In some ATC groups a ranking is introduced to help in the classification of
combination products (e.g. combinations of different antihypertensives and
combinations of different analgesics). This ranking shows which drug takes
precedence over others when the classification is decided. This is detailed in the
guidelines for the relevant drug groups.
D. Principles for changes to ATC classification
As the drugs available and their uses are continually changing and expanding,
regular revisions of the ATC system will always be necessary.
Principle
Changes in the ATC classification should be kept to a minimum. Before alterations
are made, difficulties arising for the users of the ATC system are considered and
related to the benefits achieved by the alteration.
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