ABSTRACT
The nature of conformational and configurational stereoisomerism, as well as the role of stereoisomerism in drug activity is the subject of this article. Geometric Isomerism was first defined by Wislicenus in 1887 as isomerism occurring in compounds where rotation is restricted by double bonds or ring systems. For example, several cephalosporin derivatives contain an alkoxyimino side chain that may exist in E or Z isomeric forms; the azo compound prontosil may display similar isomerism. Conformational isomerism is believed to be of great significance for drug-receptor and drug-enzyme interactions. Structural and steric complementarities of drug molecules with their target sites of action are essential criteria for the production of a pharmacological effect. Both conformational and configurational isomerism are important in the pharmacological actions of the calcium-channel-blocking 1,4-dihydropyridines. Hence it is obvious that stereoisomeric influences as well as structural effects, play a major role in the production of the pharmacological profiles of medicinal agents.
