Nomenclature of Drugs

A drug generally has three categories of names:

(a) Chemical name It describes the substance chemically, e.g.,1-(lsopropylamino)-3-(1-naphthyloxy) propan-2-ol for propranolol. This is cumbersome and not suitable for use in prescribing. A code name, e.g., RO 15-1788 (later named flumazenil) may be assigned by the manufacturer for convenience and simplicity before an approved name is coined.

(b) Non-proprietary name It is the name accepted by a competent scientific body / authority, e.g., the United States Adopted Name (USAN) by the USAN council. Similarly, there is the British Approved name (BAN) of a drug. The non-proprietary names of newer drugs are kept uniform by an agreement to use the Recommended International Non-proprietary Name (riNN) in all member countries of the WHO. The BAN of older drugs as well has now been modified to be commensurate with riNN. However, many older drugs still have more than one non-proprietary name, e.g. ‘meperidine’ and ‘pethidine’ or ‘lidocaine’ and ‘lignocaine’ for the same drugs. Until the drug is included in a pharmacopoeia, the non-proprietary name may also be called the approved name. After its appearance in the official publication, it becomes the official name.

In common parlance, the term generic name is used in place of non-proprietary name. Etymologically this is incorrect: ‘generic’ should be applied to the chemical or pharmacological group (or genus) of the compound, e.g., phenothiazines, tricyclic antidepressants, aminoglycoside antibiotics, etc. However, this misnomer is unlikely to be corrected, because of wide usage, including that in official parlance.

(c) Proprietary (Brand) name It is the name assigned by the manufacturer(s) and is his property or trade mark. One drug may have multiple proprietary names, e.g. ALTOL, ATCARDIL, ATECOR, ATEN, BETACARD, LONOL, TENOLOL, TENORMIN for atenolol from different manufacturers. Brand names are designed to be catchy, short, easy to remember and often suggestive, e.g. LOPRESOR suggesting drug for lowering blood pressure. Brand names generally differ in different countries, e.g. timolol maleate eye drops are marketed as TIMOPTIC in USA but as GLUCOMOL in India. Even the same manufacturer may market the same drug under different brand names in different countries. In addition, combined formulations have their own multiple brand names. This is responsible for much confusion in drug nomenclature.

There are many arguments for using the non-proprietary name in prescribing: uniformity, convenience, economy and better comprehension (propranolol, sotalol, timolol, pindolol, metoprolol, acebutolol, atenolol are all beta-blockers, but their brand names have no such similarity). However, when it is important to ensure consistency of the product in terms of quality and bioavailability, etc. and especially when official control over quality of manufactured products is not rigorous, it is better to prescribe by the dependable brand name.