In any science there are two basic requirements — classification and nomenclature (names): • Classification: drugs cannot be classified and named according to a single rational system because the requirements of chemists, pharmacologists, and doctors differ. • Nomenclature: nor is it practicable always to present each drug under a single name because the formulations in which they are presented as prescribable medicines may vary widely and commercial considerations are too often paramount. Generic (nonproprietary) names should be used as far as possible when prescribing except where pharmaceutical bioavailability differences have overriding importance. . | 6 SECTION I Classification and naming of drugs SYNOPSIS In any science there are two basic requirements classification and nomenclature names Classification drugs cannot be classified and named according to a single rational system because the requirements of chemists pharmacologists and doctors differ. Nomenclature nor is it practicable always to present each drug under a single name because the formulations in which they are presented as prescribable medicines may vary widely and commercial considerations are too often paramount. Generic nonproprietary names should be used as far as possible when prescribing except where pharmaceutical bioavailability differences have overriding importance. Classification Drugs may be classified by Body system . alimentary cardiovascular Therapeutic use . receptor blockers enzyme inhibitors carrier molecules ion channels Mode or site of action molecular interaction . glucoside alkaloid steroid. cellular site . loop diuretic catecholamine uptake inhibitor imipramine Molecular structure . glycoside alkaloid Any drug may have names in all three of the following classes 1. The full chemical name 2. A nonproprietary official approved generic name used in pharmacopoeias and chosen by official bodies the World Health Organization WHO chooses recommended International Nonproprietary Names rINN . The harmonisation of names began 50 years ago and It is evident from the way this book is organised that there is no homogeneous system for classifying drugs that suits the purpose of every user. Drugs are commonly categorised according to the convenience of who is discussing them clinicians pharmacologists or medicinal chemists. 1 The ATC Classification System developed by the Nordic countries and widely used in Europe meets most classification requirements. Drugs are classified according to their Anatomical Therapeutic and Chemical characteristics into five levels of specificity the fifth being that for the single .
