The difference between USAN and INN International Nonproprietary Names

An International Nonproprietary Name (INN) is the official generic, nonproprietary name given to a pharmaceutical substance or active pharmaceutical ingredient. Each INN is unique, globally recognized and public property.

WHO works closely with INN experts and national nomenclature committees to select a single internationally acceptable name for each pharmaceutical substance. To reduce the risk of confusion and medication errors, trademarks should not be derived from INNs or contain common stems used in INNs.

An established INN is known as a recommended INN (rINN), while a name still under consideration is called a proposed INN (pINN).

INNs are used in pharmacopeias, labeling, product information, scientific literature, drug regulation and as the basis for generic product names. Proposed INNs are published by WHO for public consultation, providing an opportunity to identify possible conflicts or confusion risks.

National naming systems may differ between countries. Examples include British Approved Names (BAN) and United States Adopted Names (USAN), such as the historic difference between acetaminophen and paracetamol. Through increasing international coordination, national names in countries such as Great Britain, France, Japan and the United States are now generally identical to the INN.

USAN

The USAN Program assigns United States Adopted Names through the USAN Council. The process begins when a pharmaceutical company or its representative submits an application and concludes with a formal Statement of Adoption.

Before a USAN is adopted, the sponsoring company, the USAN Council and the WHO INN Expert Group must agree on a single name for the substance.

INN and USAN names are normally assigned while a drug is still in clinical development. For INN, development should generally have progressed to clinical trials, typically around Phase II, before an application is submitted. For USAN, companies may apply during Phase I, although many wait until Phase II.

Most companies aim to have the INN and USAN available before completion of Phase III studies, allowing the name to be used in publications and, where necessary, in packaging, labeling and promotional preparations.

Timelines

An INN proposal should be submitted in line with the deadline for the relevant WHO INN Consultation, usually several months before the meeting. The WHO INN Consultation only takes place twice a year.

Applications are reviewed during the Consultation and feedback is normally provided to the applicant afterwards. If a proposed name is selected without modification, it is subsequently published as a proposed INN. Publication normally takes several months and may sometimes take longer.

Following publication, there is a four-month objection period. If no objections are received, the name can progress towards recommended INN status.

The corresponding USAN process normally follows and may require an additional few months for review and adoption for use in the United States. USAN names can be submitted throughout the year as there are no fixed deadlines or consultations.

There are no formal mechanisms to accelerate the WHO INN or USAN naming process. As a general planning assumption, approximately 8–10 months should be allowed for the INN process, with additional time for USAN. Further delays should always be considered possible.

In exceptional circumstances, an established INN or USAN may be changed, for example because of medication errors, trademark conflicts or other significant nomenclature or safety concerns.