Drug Design—A Rational Approach

Drug design may be considered as an integrated whole approach which essentially involves various steps, namely : chemical synthesis, evaluation for activity-spectrum, toxicological studies, metabolism of the drug, i.e., biotransformation and the study of the various metabolites formed, assay procedures, and lastly galenical formulation and biopharmaceutics. The ‘drug design’ in a broader sense implies random evaluation of synthetic as well as natural products in bioassay systems, creation of newer drug molecules based on biologically-active-prototypes derived from either plant or animal kingdom, synthesis of congeners displaying interesting biological actions, the basic concept of isosterism and bioisosterism, and finally precise design of a drug to enable it to interact with a receptor site efficaciously. Another terminology ‘prodrugs’ has been introduced to make a clear distinction from the widely used term ‘analogues’. Prodrugs are frequently used to improve pharmacological or biological properties. Analogues are primarily employed to increase potency and to achieve specificity of action.