Guidelines for ATC classification and DDD assignment - WHOCC

considered as a guideline since there might be changes in the meeting dates from
one year to another.
New DDDs decided at the March meeting (e.g. March 2011) will be included in the
ATC index the following year (i.e. January 2012). New DDDs decided at the
October meeting of the Working Group (e.g. October 2011) will be included in the
ATC index the year after the following year (i.e. January 2013).
2. Data requirements for submission
The following information is required when requesting a new DDD:
- Dose ranges and dosing instructions for each indication in the product
information approved by one or more major regulatory authorities.
- Doses used in clinical trials to support marketing.
- Market research data on doses used in practice in a range of countries (developed
and developing where available). The average used dose should be defined.
- Where the drug is to fit into an existing ATC classification, comparative dosing
information should be provided where it is available. It is difficult to define
therapeutically equivalent doses with the degree of precision often asked for, and
the DDDs within therapeutic groups do not necessarily represent therapeutically
equivalent doses.
- Proposal for a DDD justified by the submitted data.
- Status concerning marketing authorisation.
D. Requests for changes to DDDs
1. Procedures and timing
A change in DDDs should be proposed and explained in writing, and addressed to
the WHO Collaborating Centre for Drug Statistics Methodology. Any user may in
principle propose changes in DDDs.
All proposals for changes will be discussed by the WHO International Working
Group for Drug Statistics Methodology.
The steps in the evaluation procedure for changes to DDDs are the same as the
procedures for changes to ATC classifications (see page 38-39).
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