International nonproprietary name


An international nonproprietary name is an official generic and non-proprietary name given to a pharmaceutical drug or an active ingredient. INNs are intended to make communication more precise by providing a unique standard name for each active ingredient, to avoid prescribing errors. The INN system has been coordinated by the World Health Organization since 1953.
Having unambiguous standard names for each drug is important because a drug may be sold by many different brand names, or a branded medication may contain more than one drug. For example, the branded medications Celexa, Celapram and Citrol all contain the same active ingredient: citalopram; and the antibiotic widely known by the brand name Bactrim contains two active ingredients: trimethoprim and sulfamethoxazole. This combination of two antibiotic agents in one tablet has been available as a generic for decades, but the brand names Bactrim and Septra are still in common use.
Each drug's INN is unique but may contain a word stem that is shared with other drugs of the same class; for example, the beta blocker drugs propranolol and atenolol share the -olol suffix, and the benzodiazepine drugs lorazepam and diazepam share the -azepam suffix.
The WHO issues INNs in English, Latin, French, Russian, Spanish, Arabic, and Chinese, and a drug's INNs are often cognate across most or all of the languages, with minor spelling or pronunciation differences, for example: paracetamol paracetamolum, paracétamol and парацетамол. An established INN is known as a recommended INN, while a name that is still being considered is called a proposed INN.

Name stems

Drugs from the same therapeutic or chemical class are usually given names with the same stem. Stems are mostly placed word-finally, but in some cases word-initial stems are used. They are collected in a publication informally known as the Stem Book.
Examples are:

Stems and roots

The term stem is not used consistently in linguistics. It has been defined as a form to which affixes can be attached. Under a different and apparently more common view, this is the definition of a root, while a stem consists of the root plus optional derivational affixes, meaning that it is the part of a word to which inflectional affixes are added. INN stems employ the first definition, while under the more common alternative they would be described as roots.

Translingual communication

and pharmacotherapy are universally relevant around the world, making translingual communication about them an important goal. An interlingual perspective is thus useful in drug nomenclature. The WHO issues INNs in English, Latin, French, Russian, Spanish, Arabic, and Chinese. A drug's INNs are often cognates across most or all of the languages, but they also allow small inflectional, diacritic, and transliterational differences that are usually transparent and trivial for nonspeakers. For example, although paracetamolum has an inflectional difference from paracetamol, and although paracétamol has a diacritic difference, the differences are trivial; users can easily recognize the "same word". And although парацетамол and paracetamol have a transliterational difference, they sound similar, and for Russian speakers who can recognize Latin script or English speakers who can recognize Cyrillic script, they look similar; users can recognize the "same word". Thus INNs make medicines bought anywhere in the world as easily identifiable as possible to people who do not speak that language. Notably, the "same word" principle allows health professionals and patients who do not speak the same language to communicate to some degree and to avoid potentially life-threatening confusions from drug interactions.

Spelling regularization

A number of spelling changes are made to British Approved Names and other older nonproprietary names with an eye toward interlingual standardization of pronunciation across major languages. Thus a predictable spelling system, approximating phonemic orthography, is used, as follows:
Many drugs are supplied as salts, with a cation and an anion. The way the INN system handles these is explained by the WHO at its "Guidance on INN" webpage. For example, amfetamine and oxacillin are INNs, whereas various salts of these compounds – e.g., amfetamine sulfate and oxacillin sodium – are modified INNs.

Comparison of naming standards

Several countries had created their own nonproprietary naming system before the INN was created, and in many cases, the names created under the old systems continue to be used in those countries. As one example, in English the INN name for a common painkiller is paracetamol; the table below gives the alternative names for this in different systems:
International Nonproprietary Name
Australian Approved Name
British Approved Name paracetamol
acetaminophen

acetaminophen
Other generic names
Proprietary names
IUPAC nameN-acetamide
ATC codeN02BE01