Drug nomenclature

Drug nomenclature is the systematic naming of drugs, especially pharmaceutical drugs. In most circumstances, drugs 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 international nonproprietary names ; and trade names, which are brand names. Under the INN system, generic names for drugs are constructed out of affixes and stems that classify the drugs into useful categories while keeping related names distinguishable. A marketed drug might also have a company code or compound code.

Legal regulation

Drug names are often subject to legal regulation, including approval for new drugs and on packaging to establish clear rules about adulterants and fraudulent or misleading labeling. A national formulary is often designated to define drug names for regulatory purposes. The legally approved names in various countries include:

The World Health Organization administers the international nonproprietary name list.
A company or person developing a drug can apply for a generic name through their national formulary or directly to the WHO INN Programme. In order to minimize confusion, many of the national naming bodies have policies of maintaining harmony between national nonproprietary names and INNs. The European Union has mandated this harmonization for all member states. In the United States, the developer applies to United States Adopted Name Council, and a USAN negotiator applies to the INN on the developer's behalf.

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 in speech or in prose documents. For example, "1--3- propan-2-ol" is a chemical name for propranolol. Sometimes, a company that is developing a drug might give the drug a company code, which is used to identify the drug while it is in development. For example, CDP870 was UCB's company code for certolizumab pegol; UCB later chose "Cimzia" as its trade name. Many of these codes, although not all, have prefixes that correspond to the company name.

Nonproprietary (generic) names

Generic names are used for a variety of reasons. They provide a clear and unique identifier for active chemical substances, appearing on all drug labels, advertising, and other information about the substance. Relatedly, they help maintain clear differentiation between proprietary and nonproprietary aspects of reality, which people trying to sell proprietary things have an incentive to obfuscate; they help people compare apples to oranges. They are used in scientific descriptions of the chemical, in discussions of the chemical in the scientific literature and descriptions of clinical trials. Generic names usually indicate via their stems what drug class the drug belongs to. For example, one can tell that aciclovir is an antiviral drug because its name ends in the -vir suffix.

History

The earliest roots of standardization of generic names for drugs began with city pharmacopoeias, such as the London, Edinburgh, Dublin, Hamburg, and Berlin Pharmacopoeias. The fundamental advances in chemistry during the 19th century made that era the first time in which what is now called chemical nomenclature, a huge profusion of names based on atoms, functional groups, and molecules, was necessary or conceivable. In the second half of the 19th century and the early 20th, city pharmacopoeias were unified into national pharmacopoeias and national formularies. International pharmacopeias, such as the European Pharmacopoeia and the International Pharmacopoeia of the World Health Organization, have been the next level.
In 1953 the WHO created the International Nonproprietary Name system, which issues INNs in various languages, including Latin, English, French, Spanish, Russian, Chinese, and Arabic. Several countries also have national-level systems for creating generic drug names, including the British Approved Name system, the Australian Approved Name system, the United States Adopted Name system, and the Japanese Accepted Name system. At least several of these national-level Approved Name/Adopted Name/Accepted Name systems were not created until the 1960s, after the INN system already existed. In the 21st century, increasing globalization is encouraging maximal rationalization for new generic names for drugs, and there is an increasing expectation that new USANs, BANs, and JANs will not differ from new INNs without special justification.
During the first half of the 20th century, generic names for drugs were often coined by contracting the chemical names into fewer syllables. Such contraction was partially, informally, locally standardized, but it was not universally consistent. In the second half of the 20th century, the nomenclatural systems moved away from such contraction toward the present system of stems and affixes that show chemical relationships.
Biopharmaceuticals have posed a challenge in nonproprietary naming because unlike smaller molecules made with total synthesis or semisynthesis, there is less assurance of complete fungibility between products from different manufacturers. Just as wine may vary by strain of yeast and year of grape harvest, so each product can be subtly different because living organisms are an integral part of production. The WHO MedNet community continually works to augment its system for biopharmaceuticals to ensure continued fulfillment of the goals served by having nonproprietary names. In recent years the development of the Biological Qualifier system has been an example.
The prefixes and interfixes have no pharmacological significance and are used to separate the drug from others in the same class. Suffixes or stems may be found in the middle or more often the end of the drug name, and normally suggest the action of the drug. Generic names often have suffixes that define what class the drug is.

List of stems and affixes

More comprehensive lists can be found in Appendix VII of the USP Dictionary or in the WHO INN stembook.

Stem	Drug class	Example
-vir	Antiviral drug	aciclovir, oseltamivir
-cillin	Penicillin-derived antibiotics	penicillin, carbenicillin, oxacillin
cef-	Cephem-type antibiotics	cefazolin
-mab	Monoclonal antibodies	trastuzumab, ipilimumab
-ximab	Chimeric antibody, in which the design of the therapeutic antibody incorporates parts of multiple different antibodies, for example, in the case of infliximab, variable regions from a mouse anti-TNF antibody and constant regions from human antibodies	infliximab
-zumab	humanized antibody	natalizumab, bevacizumab
-anib	Angiogenesis inhibitors	pazopanib, vandetanib
-ciclib	Cyclin-dependent kinase 4/CDK6 inhibitors	palbociclib, ribociclib
-degib	hedgehog signaling pathway inhibitors	vismodegib, sonidegib
-denib	IDH1 and IDH2 inhibitors	enasidenib, ivosidenib
-lisib	Phosphatidylinositol 3-kinase inhibitors	alpelisib, buparlisib
-parib	PARP inhibitor	olaparib, veliparib
-rafenib	BRAF inhibitors	sorafenib, vemurafenib
-tinib	Tyrosine-kinase inhibitors	erlotinib, crizotinib
-zomib	proteasome inhibitors	bortezomib, carfilzomib
-vastatin	HMG-CoA reductase inhibitor	atorvastatin
-prazole	Proton-pump inhibitor	omeprazole
-lukast	Leukotriene receptor antagonists	zafirlukast, montelukast
-grel-	Platelet aggregation inhibitor	clopidogrel, ticagrelor
-axine	Dopamine and serotonin–norepinephrine reuptake inhibitor	venlafaxine
-olol	Beta-blockers	metoprolol, atenolol
-oxetine	Antidepressant related to fluoxetine	duloxetine, reboxetine
-sartan	Angiotensin receptor antagonists	losartan, valsartan
-pril	Angiotensin converting enzyme inhibitor	captopril, lisinopril
-oxacin	Quinolone-derived antibiotics	levofloxacin, moxifloxacin
-barb-	Barbiturates	phenobarbital, secobarbital
-xaban	Direct Xa inhibitor	apixaban, rivaroxaban
-afil	Inhibitor of PDE5 with vasodilator action	sildenafil, tadalafil
-prost-	Prostaglandin analogue	latanoprost, unoprostone
-ine	Alkaloids and organic bases	atropine, quinine
-tide	Peptides and glycopeptides	nesiritide, octreotide
-vec	Gene therapy vectors	Alipogene tiparvovec
-ast	Anti-asthmatic	zafirlukast, seratrodast
-caine	local anesthetic	benzocaine
-dipine	Calcium channel blocker derived from dihydropyridine	amlodipine, nifedipine, felodipine
-tidine	H2 receptor antagonist	cimetidine, ranitidine, famotidine
-setron	5-HT3 antagonist	ondansetron, granisetron, palonosetron
-mycin	Antibiotic produced by Streptomyces strains	vancomycin, streptomycin, Neomycin