Guidelines for ATC classification and DDD assignment - WHOCC

It is open to anyone with a legitimate interest in the Anatomical Therapeutic
Chemical (ATC) classification system and Defined Daily Dose (DDD) assignment.
This includes regulatory authorities, the pharmaceutical industry, academia and
non-governmental organisations.
It provides an opportunity for these persons to present additional information to the
experts to assist them in their decision making.
It provides an opportunity for the international experts of the Working Group to
exchange ideas and opinions with interested parties.
It is not intended to be used as a mechanism to challenge the decision of the
Working Group. The procedures for applying for and commenting on an ATC
classification or a DDD assignment are outlined in these Guidelines (see section V).
Interested parties are requested to register for this session to WHO Headquarter at
least 14 days in advance of the meeting and are requested to provide a relevant
reason for attending. WHO Headquarter will restrict the time allowed for each
presentation in order to keep the duration of the open session within 1.5 hours.
Information on these meetings will be made available on the WHO website at
www.who.int/medicines.
C. The purpose of the ATC/DDD system
The purpose of the ATC/DDD system is to serve as a tool for drug utilization
research in order to improve quality of drug use. One component of this is the
presentation and comparison of drug consumption statistics at international and
other levels.
A major aim of the Centre and Working Group is to maintain stable ATC codes and
DDDs over time to allow trends in drug consumption to be studied without the
complication of frequent changes to the system. There is a strong reluctance to
make changes to classifications or DDDs where such changes are requested for
reasons not directly related to drug consumption studies. For this reason the
ATC/DDD system by itself is not suitable for guiding decisions about
reimbursement, pricing and therapeutic substitution.
The classification of a substance in the ATC/DDD system is not a
recommendation for use, nor does it imply any judgements about efficacy or
relative efficacy of drugs and groups of drugs.
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