International Nonproprietary Names

International Nonproprietary Names (INN) identify pharmaceutical substances or active pharmaceutical ingredients. Each INN is a unique name that is globally recognized and is public property. A nonproprietary name is also known as a generic name. The INN system is managed by the World Health Organization (WHO).

History of the International Nonproprietary Names System

The INN system was established in 1950 by the World Health Assembly and the first list of International Nonproprietary Names for pharmaceutical substances was published in 1953. The cumulative list of INN now stands at some 7000 names designated since that time, and this number is growing every year by some 120-150 new INN.

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 INN, 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, INN have to be distinctive in sound and spelling, and should not be liable to confusion with other names in common use. To make INN 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.

Use of International Nonproprietary Names

Nonproprietary names are intended for use in pharmacopoeias, labeling, product information, advertising and other promotional material, drug regulation and scientific literature, and as a basis for product names, e.g. for generics.

As a result of ongoing collaboration, national names such as British Approved Names (BAN), Dénominations Communes Françaises (DCF), Japanese Adopted Names (JAN) and United States Accepted Names (USAN) are nowadays, with rare exceptions, identical to the INN. These national naming schemes can be country specific. That is, they refer to ingredients used in the particular country with names intended to meaningful to its citizens. As a result, there is significant overlap and yet some differences between various national schemes. For example, differences exist between BAN and USAN names for the same substance (e.g. acetaminophen is also called paracetamol). In addition to having different names for the same substances, different countries permit the use of different medicinal ingredients. It is assured that all US medications do not have approved names under other countries' naming schemes. Likewise, these international naming schemes cover medications not currently employed in the USA.

To avoid confusion, which could jeopardize the safety of patients, trade-marks cannot be derived from INN and, in particular, must not include their common stems. The creation of further names within a series would be seriously hindered by the use of a common stem in a brand-name.

Modified International Nonproprietary Names (INNM)

In principle, INN are selected only for the active part of the molecule which is usually the base, acid or alcohol. In some cases, however, the active molecules need to be expanded for various reasons, such as formulation purposes, bioavailability or absorption rate. In 1975 the experts designated for the selection of INN decided to adopt a new policy for naming such molecules. In future, names for different salts or esters of the same active substance should differ only with regard to the inactive moiety of the molecule. For example, oxacillin and ibufenac are INN and their salts are named oxacillin sodium and ibufenac sodium. The latter are called modified INN (INNM).

Before the existence of this rule, some INN were published for salts. In such cases, the term "modified INN" may also be used for a base or acid. For example, levothyroxine sodium was published as an INN and levothyroxine may thus be referred to as an INNM.

Return to the International Drug Name Database.