Nomenclature of Drugs

November 12, 2021


A drug is defined as a chemical substance of known structure, which when administered to a living organism, produces a biological effect. Drug may be a synthetic chemical, chemical obtained from plants or animals, or a product of genetic engineering. Medicine is a chemical preparation, which usually contains one or more drugs and other substances such as excipients, stabilizers or solvents, etc. administered to produce a therapeutic effect.

Drug nomenclature is the systematic naming of pharmaceutical drugs. Usually, three types of names are given to a drug which are:

  • Chemical names, the most important of which is the IUPAC name.
  • Generic or non-proprietary names. The most important of which is the International Non-Proprietary Name (INNs).
  • Trade name, brand name or Proprietary name

A marketed drug might also have a company code or a compound code.

For example, naming a commonly used fever lowering medicine is:

  • Chemical name: N-(4-hydroxy phenyl) acetamide.
  • Generic name : paracetamol
  • Brand name is Tylenol, Adol ,Panadol, others

The chemical name is the scientific name based on the molecular structure of a drug. There are various systems of chemical nomenclature and so many names are given to a substance. The most important name is that is given by the IUPAC ( International Union of Pure and Applied Chemistry). Chemical names are often long and complex and rarely used to identify a drug. Chemical names are necessary to give absolute definition to a compound.

The Brand names (proprietary or trade name) are created by the company which patents the drug. Under the patent, the company has an exclusive right to produce and sell the drug for a definitive period. It is the commercial property of a pharmaceutical company.

Many countries have their national pharmacopeias. Due to vast development in the field of medicine and globalization, in 1953 WHO created the International Non-Proprietary Naming System to give a unique standard name for each active ingredient to avoid confusion. Several countries also have their national system for creating generic names, such as British Applied Names (BAN), and the United States Adopted Names (USAN). WHO collaborates closely with INN experts and national nomenclature committees to select a single name of worldwide acceptance for each active substance that is to be marketed as a pharmaceutical substance. INNs are issued in various languages ( English, Latin, French, Spanish, Russian, Chinese, and Arabic). INNs in different languages have minor spelling or pronunciation differences. INNs are intended to make communication more precise by providing a unique standard name for each active ingredient, to avoid prescribing errors. Having standard names for each drug is important because a drug may be sold by many different brand names causing unnecessary confusion.

Each medicine INN is unique. Under the INNs, the generic names are constructed out of affixes and stems that classify a medicine in different categories. A stem or root may be found in the middle or most often at the end of a drug name which suggests its action and class of drug.

Some examples of stems, drug class, and examples of drugs are:

Stems Class of DrugDrug examples
-cillinPenicillin derived antibioticsAmpicillin
Amoxicillin
-virAntiviral drugsAciclovir
Oseltamivir
-prilAngiotensin converting
enzyme inhibitors
Captopril
Lisinopril
-vastatincholesterol-lowering drugs
(HMG-CoA Inhibitors)
Simvastatin
Atrovastatin
-azepamBenzodiazepinesDiazepam
Lorazepam

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