International Nonproprietary Name

An International Nonproprietary Name (INN; also known as rINN, for recommended International Nonproprietary Name or pINN for proposed International Nonproprietary Name) is the official nonproprietary or generic name given to a pharmaceutical substance, as designated by the World Health Organization (WHO). The plethora of named proprietary preparations containing a given substance can lead to confusion about the identity of the active ingredient. INNs facilitate communication by providing a standard name for each substance; they are designed to be unique and distinct so as to avoid confusion in prescribing. A similar role is played in chemistry by IUPAC names, though those are less suited to common usage, being typically very long and unwieldy.

WHO issues INNs in English, Latin, French, Russian, and Spanish; Arabic and Chinese versions, although not included in the original scheme, are now also being issued.

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:
 * -coxib for COX-2 inhibitors, a type of anti-inflammatory drugs (e.g. celecoxib)
 * -mab for monoclonal antibodies (e.g. infliximab); see Nomenclature of monoclonal antibodies
 * -olol for beta blockers (e.g. atenolol)
 * -oxetin for fluoxetine derivatives, a group of antidepressants
 * -pril for ACE inhibitors (e.g. captopril)
 * -vastatin for HMG-CoA reductase inhibitors, a group of cholesterol lowering agents (e.g. simvastatin)
 * io- for iodine containing radiopharmaceuticals (e.g. iobenguane)

Linguistic discussion
The term stem is not used consistently in linguistics. It has been defined as a form to which affixes (of any type) 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.

Name changes
A number of modifications are made to British Approved Names and other older nonproprietary names. This is to ensure similar pronunciation across major languages:


 * ae and oe are replaced by e
 * ch is replaced by c
 * ph is replaced by f
 * th is replaced by t
 * y is replaced by i