Guidelines on the Use of International Nonproprietary Names (INNs) for Pharmaceutical Substances
(1997; 41 pages) View the PDF document
Table of Contents
Close this folder1. General introduction
View the document1.1 General information on the INN system
View the document1.2 Use of INNs
Open this folder and view contents2. Elements in the INN system
Open this folder and view contents3. Principles for selection of INNs
View the document4. Protection of INNs
Open this folder and view contents5. How to apply for an INN
View the document6. References for supporting material
View the documentAnnex 1: Background information on the INN programme
View the documentAnnex 2: General principles for guidance in devising international nonproprietary names for pharmaceutical substances
View the documentAnnex 3: List of common stems used in the selection of INNs
View the documentAnnex 4: Specific groups of biological compounds
View the documentAnnex 5: WHA46.19 - Nonproprietary names for pharmaceutical substances
View the documentAnnex 6: Procedure for the selection of international nonproprietary names for pharmaceutical substances
View the documentAnnex 7: Applications for INNs through national authorities (addresses)
View the documentAnnex 8: INN request form

1.1 General information on the INN system

An International Nonproprietary Name (INN) identifies a pharmaceutical substance or active pharmaceutical ingredient by a unique name that is globally recognized and is public property. A nonproprietary name is also known as a generic name.

The INN system as it exists today was initiated in 1950 by a World Health Assembly resolution WHA3.11 and began operating in 1953, when the first list of International Nonproprietary Names for pharmaceutical substances was published. The cumulative list of INNs now stands at some 7000 names designated since that time, and this number is growing every year by some 120-150 new INNs.

Since its inception, the aim of the INN system has been to provide health professionals with a unique and universally available designated name to identify each pharmaceutical substance. The existence of an international nomenclature for pharmaceutical substances, in the form of INNs, is important for the clear identification, safe prescription and dispensing of medicines to patients, and for communication and exchange of information among health professionals and scientists worldwide.

As unique names, INNs have to be distinctive in sound and spelling, and should not be liable to confusion with other names in common use. To make INNs universally available they are formally placed by WHO in the public domain, hence their designation as “nonproprietary”. They can be used without any restriction whatsoever to identify pharmaceutical substances.

Another important feature of the INN system is that the names of pharmacologically-related substances demonstrate their relationship by using a common “stem”. By the use of common stems the medical practitioner, the pharmacist, or anyone dealing with pharmaceutical products can recognize that the substance belongs to a group of substances having similar pharmacological activity. For example all iodine-containing contrast media are given the prefix io-, while all ß-adrenoreceptor antagonists the suffix -olol. The use of stems is described later in more detail.

The extent of INN utilization is expanding with the increase in the number of names. Its wide application and global recognition are also due to close collaboration in the process of INN selection with numerous national drug nomenclature bodies. The increasing coverage of the drug-name area by INNs has led to the situation whereby the majority of pharmaceutical substances used today in medical practice are designated by an INN. The use of INNs is already common in research and clinical documentation, while the importance of the programme is growing further due to expanding use of generic names for pharmaceutical products.

The names which are given the status of an INN are selected by the World Health Organization on the advice of experts from the WHO Expert Advisory Panel on the International Pharmacopoeia and Pharmaceutical Preparations. The process of INN selection follows three main steps:

• a request/application is made by the manufacturer or inventor,

• after a review of the request a proposed INN (prop. INN) is selected and published for comments,

• after a time-period for objections has lapsed, the name will obtain the status of a recommended INN (rec. INN) and is published as such.

The procedures relating to each of these steps are described in the present document in full detail.

INNs are selected in principle only for single, well-defined substances that can be unequivocally characterized by a chemical name (or formula). It is the policy of the INN programme not to select names for mixtures of substances, while substances that are not fully characterized are included in the INN system in exceptional cases only. INNs are not selected for herbal substances (vegetable drugs) or for homoeopathic products. It is also the policy of the INN programme not to select names for those substances that have a long history of use for medical purposes under well-established names such as those of alkaloids (e.g. morphine, codeine), or trivial chemical names (e.g. acetic acid).

The INN is usually designated for the active part of the molecule only, to avoid the multiplication of entries in cases where several salts, esters, etc. are actually used. In such cases, the user of the INN has to create a modified INN (INNM) himself; mepyramine maleate (a salt of mepyramine with maleic acid) is an example of an INNM. When the creation of an INNM would require the use of a long or inconvenient name for the radical part of the INNM, the INN programme will select a short name for such a radical (for example, mesilate for methanesulfonate).

Names of pharmaceutical preparations, such as used in pharmacopoieal monograph titles, usually consist of two elements, the first designating the active substance (an INN is used here), and the other designating the dosage form of the product. Rules for creating such names fall outside the INN programme and are not discussed here.

In the process of INN selection, the rights of existing trade-mark owners are fully protected. If in the period of four months following the publication of a proposed INN, a formal objection is filed by an interested person who considers that the proposed INN is in conflict with an existing trade-mark, WHO will actively pursue an arrangement to obtain a withdrawal of such an objection or will reconsider the proposed name. As long as the objection exists, WHO will not published it as a recommended INN.

With the growing number of INNs and trade-marks, the possibility of conflicts between the two has gradually increased, even with full protection of the rights of existing trade-marks. The main source of conflict is usually an attempt by a manufacturer to propose a new trade-mark containing stems established in the INN programme. If protection is granted to such a name, this may diminish the freedom of the INN programme in selecting further INNs in the same series of substances. To prevent such occurrences, the matter was taken up in a resolution of the World Health Assembly WHA46.19. This issue is discussed in more detail in section 4.

Further background information on the INN programme may be found in Annex 1.

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