Drug Nomenclature

DRUG NOMENCLATURE

A drug generally has three categories of names:

Chemical name

It describes the substance chemically, e.g. 1(Isopropylamino)3(1naphthyloxy) propan2ol for propranolol. This is cumbersome and not suitable for use in prescribing. A code name, e.g. RO 151788 (later named flumazenil) may be assigned by the manufacturer for convenience and simplicity before an approved name is coined.

(b) Nonproprietary 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 nonproprietary names of newer drugs are kept uniform by an agreement to use the Recommended International Nonproprietary 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 nonproprietary names, e.g. ‘meperidine’ and ‘pethidine’ or ‘lidocaine’ and ‘lignocaine’ for the same drugs. Until the drug is included in a pharmacopoeia, the nonproprietary 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 nonproprietary 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 nonproprietary name in prescribing: uniformity, convenience, economy and better comprehension (propranolol, sotalol, timolol, pindolol, metoprolol, acebutolol, atenolol are all β 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.

Essential Drugs (Medicines) Concept

The WHO has defined Essential Drugs* (medicines) as “those that satisfy the priority healthcare needs of the population. They are selected with due regard to public health relevance, evidence on efficacy and safety, and comparative cost effectiveness. Essential medicines are intended to be available within the context of functioning health systems at all times and in adequate amounts, in appropriate dosage forms, with assured quality and adequate information, and at a price the individual and the community can afford.

It has been realized that only a handful of drugs out of the multitude available can meet the health care needs of majority of the people in any country, and that many well tested and cheaper drugs are equally (or more) efficacious and safe as their newer more expensive congeners. For optimum utilization of resources, governments (especially in developing countries) should concentrate on these drugs by identifying them as Essential medicines. The WHO has laid down criteria to guide selection of an essential medicine.

Adequate data on its efficacy and safety should be available from clinical studies.

It should be available in a form in which quality, including bioavailability, and stability on storage can be assured.

Its choice should depend upon pattern of prevalent diseases; availability of facilities and trained personnel; financial resources; genetic, demographic and environmental factors.

In case of two or more similar medicines, choice should be made on the basis of their relative efficacy, safety,

In the 12th list (2003) the terminology has been changed from “essential drugs” to “essential medicines” to denote pharmaceutical preparations used in clinical healthcare practice, because often the term ‘drugs’ is understood to mean illicit substances quality, price and availability. Cost benefit ratio should be a major consideration.

Choice may also be influenced by comparative pharmacokinetic properties and local facilities for manufacture and storage.

 Most essential medicines should be single compounds. Fixed ratio combination products should be included only when dosage of each ingradient meets the requirements of a defined population group, and when the combination has a proven advantage in therapeutic effect, safety, adherence or in decreasing the emergence of drug resistance.

Selection of essential medicines should be a continuous process which should take into account the changing priorities for public health action, epidemiological conditions as well as availability of better medicines/ formulations and progress in pharmacological knowledge.

Recently, it has been emphasized to select essential medicines based on rationally developed treatment guidelines.

To guide the member countries, the WHO brought out its first Model List of Essential Drugs along with their dosage forms and strengths in 1977 which could be adopted after suitable modifications according to local needs. This has been revised from time to time and the current is the 15^th list (2007). India produced its National Essential Drugs List in 1996 and has revised it in 2003 with the title “National List of Essential Medicines”. This includes 354 medicines which are considered to be adequate to meet the priority healthcare needs of the general population of the country. An alphabetical compilation of the WHO as well as National essential medicines is presented.

Adoption of the essential medicines list for procurement and supply of medicines, especially in the public sector healthcare system, has resulted in improved availability of medicines, cost saving and more rational use of drugs.

Orphan Drugs

These are drugs or biological products for diagnosis/treatment/ prevention of a rare disease or condition, or a more common disease (endemic only in resource poor countries) for which there is no reasonable expectation that the cost of developing and marketing it will be recovered from the sales of that drug. The list includes sodium nitrite, fomepizole, liposomal amphotericin B, ancrod, rifabutin, succimer, somatropin, digoxin immune Fab (digoxin antibody), liothyronine (T₃) and many more. Though these drugs may be life saving for some patients, they are commercially difficult to obtain. Governments in developed countries offer tax benefits and other incentives to pharmaceutical companies for developing and marketing orphan drugs (e.g. Orphan Drug Act in USA).