Drug Nomenclature

Drug nomenclature is the systematic naming of drugs, especially pharmaceutical drugs. Drugs, in the majority of circumstances, have 3 types of names: chemical names, the most important of which is the IUPAC name; generic or nonproprietary names, the most important of which are the International Nonproprietary Names (INNs); and trade names, which are brand names. Generic names for drugs are nowadays constructed out of affixes and stems that classify the drugs into different categories and also separate drugs within categories. A marketed drug might also have a company code or compound code.

Chemical names

The chemical names are the scientific names, based on the molecular structure of the drug. There are various systems of chemical nomenclature and thus various chemical names for any one substance. The most important is the IUPAC name. Chemical names are typically very long and too complex to be commonly used in referring to a drug.[1] Sometimes, a company that is developing a drug might give the drug a company code,[3] which is used to identify the drug while it is in development. For example, CDP870 is UCB’s company code for Cimzia.[1] Many of these codes, although not all, have prefixes that correspond to the company name. Example: 1-(Isopropylamino)-3-(1-naphthyloxy) propan-2-ol (propranolol).

Nonproprietary (generic) names

During development, the company will apply for regulatory approval of the drug by the relevant national regulatory agency (such as the U.S. Food and Drug Administration [FDA]), and it will apply for a generic (nonproprietary) name for that country (such as the United States Adopted Name [USAN] or Japanese Accepted Name [JAN]). It will also apply for an International Nonproprietary Name (INN) through the World Health Organization (WHO). Nowadays the national nonproprietary names are usually the same as the INN. The generic names usually indicate via their stems what drug class the drug belongs to.[4] For example, one can tell that aciclovir is an antiviral drug because its name ends in the -vir suffix.

Combination drug products

For combination drug products—those with 2 or more drugs combined into 1 dosage form—single nonproprietary names beginning with “co-” exist in both British Approved Name (BAN) form and in a formerly maintained USP name called the pharmacy equivalent name (PEN). Otherwise the 2 names are simply both given, joined by hyphens or slashes. For example, suspensions combining trimethoprim and sulfamethoxazole are called either trimethoprim/sulfamethoxazole or co-trimoxazole. Similarly, co-codamol is codeineacetaminophen, and co-triamterzide is triamterenehydrochlorothiazide. The USP ceased maintaining PENs, but the similar “co”-prefixed BANs are still current.

Trade (brand) names

For drugs that make it all the way through development, testing, and regulatory acceptance, the pharmaceutical company then gives the drug a trade name. The term trade name is a standard term in the pharmaceutical industry for a brand name or trademark name. For example, Lipitor is Pfizer‘s trade name for atorvastatin, a cholesterol-lowering medication.


An international nonproprietary name (INN) is an official generic and nonproprietary name given to a pharmaceutical drug or active ingredient.[2] International nonproprietary names make communication more precise by providing a unique standard name for each active ingredient, to avoid prescribing errors.[1] The INN system has been coordinated by the World Health Organization (WHO) since 1953.

Having unambiguous standard names for each drug (standardization of drug nomenclature) 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 branded preparation Lemsip contains two active ingredients: paracetamol and phenylephrine.

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” (en) “paracetamolum” (la), “paracétamol” (fr) and “парацетамол” (ru). An established INN is known as a recommended INN (rINN), while a name that is still being considered is called a proposed INN (pINN).


Name Stem examples are:[3]