Nomenclaure of Drugs

Chemical, Drug and Brand Names

Chemical Names

Chemical name (aka IUPAC name) is a systematic name. The International Union of Pure and Applied Chemists (IUPAC) gives a set of rules to dictate how chemicals (including drug molecules) are to be named according to the connections between every atom in the molecule. As such, any chemist can use the IUPAC rules to convert the chemical name into the chemical structure (or vice versa). This naming system is very useful for chemists who are synthesising new chemicals because they can instantly apply the IUPAC rules to assign a name to their new chemical and easily communicate with other chemists. But systematic chemical names of complex molecules (such as many drugs) can be lengthy and difficult to communicate (eg (RS)-1-[4-(2-methoxyethyl)phenoxy]-3-[(propan-2-yl)amino]propan-2-ol). Therefore, there’s a clear need for a naming system that is useful for pharmacologists and clinicians. This is where drug names come in.

Drug Names

Drug names (aka common names) are easier to pronounce (the above chemical name is “metoprolol”) standardised but non-systematic. Standardised because there is only one unique drug name referring to only one chemical entity. Non-systematic because you cannot derived the structure of the drug molecule from the drug name or vice versa. Instead, drug names are bestowed by the World Health Organisation International Nonproprietary Name (INN) Programme. The INN name is given to new drugs to aid communication amongst clinicians (doctors, nurses, pharmacists, dentists) and pharmacology researchers. INN follows loose rules which, as a side effect, make it easier for students to group drugs. For example, within the medications for high blood pressure, drugs with the same target will have the same ending (suffix). Some examples are shown below

Antihypertensive drug classes use consistent naming conventions in the form of suffixes to indicate the molecular target of the drug.

Target	Suffix	Examples
β adrenoreceptor	‑olol	metoprolol propranolol bisoprolol atenolol
angiotensin converting enzyme	‑pril	lisinopril ramipril perindopril enalapril
angiotensin II receptor	‑sartan	candasartan valsartan telmisartan irbesartan
L-type calcium channel	‑dipine	amlodipine nifedipine lercanidipine felodipine

Brand Names

Lastly, brand names (aka proprietary names) are catchy names dreamt up by marketing teams in pharmaceutical companies to help promote their drug to patients and clinicians. They and are intended to be memorable, easy to pronounce and attractive to the patient. For example, consider one of the high blood pressure drug listed above, metoprolol. It is marketed under the brand name “Lopressor®”—it LOwers blood PRESSure! They are a registered trademark of the company who produces the brand.

The brand name is different from the manufacturer name. Lopressor® is manufactured by the company Novartis however the company Astra Zeneca also manufactures metoprolol under the brand name Betaloc®. Both Novartis and Astra Zeneca are huge pharmaceutical companies who manufacture hundreds of other brands of drugs.

Dispite being more appealing to the patient, brand names can cause some confusion and lead to incorrect assumptions about the quality across different brands. Early in the drug’s lifecycle it is patented and only one pharmaceutical company can sell it. During this time, there is only be one brand of the drug available—the innovator brand. When drugs patents expire after a couple of decades, anyone can start manufacturing, marketing and selling the same drug under their own brand name (usually much cheaper). In each brand, the active component (the drug) is identical and acts in the same way in the body.

Comparison of features of chemical (IUPAC) name, drug (generic) names and brand (proprietary) names.

	Chemical (IUPAC) name	Drug (common) name	Brand (proprietary) name
Example	(RS)-1-[4-(2-methoxyethyl)phenoxy]-3-[(propan-2-yl)amino]propan-2-ol	metoprolol	Lopressor® Betaloc® Minax® Metoprolol Sandoz®
Origin	Determined systematically following the strict IUPAC rules	Given by WHO INN programme following loose rules	Created by pharmaceutical company marketing team
Purpose	Precise, unambiguous clarity	Easier communication	Marketing
Users	Chemists	Pharmacologists Clinicians (doctors, nurses, pharmacists, dentists) Some patients	Pharma companies Patients Some clinicians
Advantanges	Very precise Very descriptive (ie of the chemical structure)	Often descriptive (ie of the pharmacology) Avoids confusion Facilitates international communication	Easy to remember Fosters company loyalty
Disadvantages	Very difficult to communicate Can be very difficult to remember	Sometimes harder to pronounce Sometime unappealing Not systematic	Can cause confusion Not systematic or standardised Can cause incorrect assumptions about product quality

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