ATC Application

Application form

Applications for ATC are in a transitional period only available on our old site.

ATC codes

Data requirements

The following data should be submitted when requesting an ATC code for a substance:

• Chemical structure and relationship to similar drugs
• Pharmacology and mechanism of action and relationships to similar drugs
• Main indication as shown in the product information in major countries where it is licensed or submitted for licensing
• Other indications which are licensed or for which licensing is proposed in the future
• Proposed ATC classification with justification based on the evidence submitted
• Status concerning marketing authorisation
• Information about therapeutic use, if available

Useful sources of these data would be approved product information documents from regulatory authorities or proposed product information documents stating that these are not yet approved.  Summaries of submissions to, or evaluations from, major regulatory agencies relating to the above are useful, as well as market research data showing the percentage use for the main indications.

Procedure

All new entries in the ATC classification system are assigned on request from the users. Requests for ATC classification of a medicinal substance should be addressed to the WHO Collaborating Centre for Drug Statistics Methodology in Oslo, Norway (Application form).  Application for ATC is free of charge. The official language of the ATC/DDD Centre is English. Requests and documentation should accordingly be submitted in English. 

If a substance marketed in a country is not included in the latest version of the annually updated ATC classification index, a request for an ATC code may in principle be sent from any user of the system (e.g. health authorities, pharmaceutical manufacturers, researchers and other users).  It will usually be the manufacturer who has best access to the information required for an application.  The manufacturer will usually wish to know about and be involved in an application for an ATC classification and/or DDD assignment for one of their products, particularly if it is a new drug. 

A new chemical entity is normally not included in the ATC system before an application for marketing authorisation is ready for submission in at least one country.  In some cases, it may be necessary to await a classification until the new medicinal product has been approved in at least one country (especially for chemical entities where it is considered difficult to establish a new 5th level).  These conditions are set to avoid including in the ATC system too many chemical entities which never reach the market.

It is left to the national users of the ATC system to classify combination products based on the principles given in these guidelines.  The guidelines are prepared in order to facilitate this work and to ensure that different users of the ATC system classify in a consistent way.  If the content of these guidelines is not sufficient to decide a classification of a specific combination, or if it is necessary to establish a new ATC entry, such problems should be addressed to the ATC/DDD Centre in Oslo.  The ATC/DDD Centre also provides regular training courses to assist those working with the system at a national level.

The WHO International Working Group for Drug Statistics Methodology formally approves all new ATC codes.  The group has two annual meetings, normally in March and October.

The steps in the approval procedure for new ATC codes are normally as follows:

• A standard letter confirming receipt of the request is returned from the ATC/DDD Centre to the applicant.
• If the new code is easy to assign, a preliminary ATC code assigned by the ATC/DDD Centre is returned to the applicant within 6-8 weeks, informing them that the ATC code still has to be formally approved by the Working Group at the next meeting.
• For substances with more than one alternative classification and for substances, which are difficult to classify into existing classifications, the requests are discussed in the Working Group before assignment of a temporary ATC code. The applicant receives this information within 6-8 weeks after receipt of the request. After approval of the minutes of the Working Group meetings, the decision of the temporary ATC code is sent from the ATC/DDD Centre to the applicant.
• After approval of the minutes of the Working Group meeting the new ATC codes approved at the meeting are published on this website (New ATC codes and alterations) and in the next issue of the publication WHO Drug Information.  A deadline will then be allowed for interested parties to comment or object to the decisions. 
• If objections, justified on evidence submitted, are received, the ATC classification will be discussed again at the following meeting of the Working Group.  If the decision is kept, then the decision is considered final after this meeting.  If a new decision is taken by the Working Group, notification of this new ATC is published at on this website (New ATC codes and alterations) and in the next issue of the publication WHO Drug Information. A deadline is then allowed for any interested parties to comment or object to the decision.
• If no objections are received, the new ATC code is considered final and included in the next issue of the ATC classification index. A new code can be used when it is considered final. A list of new final ATC codes is also published semi-annually on this website (New ATC codes and alterations) and in the WHO Drug Information.

ATC alterations

Principles for ATC alterations

As the selection of drugs and their uses are continually changing and expanding, regular revisions of the ATC system will always be necessary.

Changes in the ATC classification should be kept to a minimum.  An important aim is to keep a stable classification system over time with as few changes as possible and still have a classification where new therapy and new pharmacological principles find an appropriate place.  Before alterations are made, any potential difficulties for the use of the ATC system in drug utilization monitoring and research are considered and related to the benefits that could be achieved by the alteration.

Alterations in ATC classification can be made when the main use of a drug has clearly changed, and when new groups are required to accommodate new substances or to achieve better specificity in the groupings.  Other reasons for changes can be new knowledge about mechanism of action or the need for splitting large and complex groups.

When it is decided to make an alteration, the following principles are used:

• When new therapeutic or pharmacological ATC groups are assigned, it should always be considered if there are substances in other groups that should be included in the new group.
• When changing ATC codes for plain products, it should always be considered if it is necessary to change the ATC code for any combination products with the same active ingredient.
• When an ATC code is changed for a substance, the previous code is not reused for new substances.

When an ATC code is altered, the DDD is also reviewed. For example, when the classification of chloroquine was changed from ATC group M to P (i.e. classified only as an antimalarial), the DDD was changed since the dosages used for treatment of malaria are different from the dosages used for rheumatic disorders.

A cumulative overview of all ATC alterations back to 2005 is available on the website.

Data requirement

When requesting changes to ATC classifications, the data requirements are similar to the data required for new ATC codes.  An important basis for the ATC/DDD system is to maintain a stable system for drug consumption studies.  For this reason, there need to be compelling reasons for changing ATC codes.  It is therefore important to submit data, which justify the proposed change.

If a change in the main therapeutic use is the reason for the proposed change, the data submitted should clearly indicate this change (e.g. market research data showing the percentage use for the different indications in a range of countries).

If new knowledge of pharmacology or mechanism of action is the reason for the proposed change, relevant evidence should be submitted.

If the proposed change is to establish specific ATC groups for one or more substances already classified in another group (usually a various group), it is necessary to submit data that verify that the change is beneficial and represents an improvement of the ATC classification for presenting drug consumption statistics.  Justifications based on the use of the system in reimbursement, for pricing or marketing reasons will not be considered.

Procedures

Any user may in principle propose changes to ATC classifications.  There is no application form for ATC alterations. Proposal for changes should be sent to the WHO Collaborating Centre for Drug Statistics Methodology, and all proposals will be discussed in the WHO International Working Group for Drug Statistics Methodology.

The steps in the evaluation procedure for changes to ATC classifications are as follows:

• The ATC/DDD Centre will confirm receipt of the proposal for a change and give information about the time schedule for discussion at the Working Group meeting.
• After approval of the minutes of the Working Group meeting, the decision from the meeting concerning the proposed change is distributed from the ATC/DDD Centre to those requesting the change (the applicant).  Independent of whether it has been decided to change or not, a deadline will be allowed for the applicant to comment or object to this decision.
• If it is decided to make a change, notification of this change is published on the website (New ATC codes and alterations) and in the next issue of the publication WHO Drug Information.
• If objections, justified by submitted evidence, are received, the ATC alteration will be discussed again at the following meeting of the Working Group, and a final decision will then be taken.
• If no objections are received, the altered ATC classification will be implemented in the next issue of the ATC classification index.