Abstract: Drug designing is a complex process and requires expertise from various fields like medicinal chemistry, biochemistry, pharmaceutics, pharmacology and toxicology, molecular modeling etc. Discovery or identification process of a suitable candidate may employ methods like serendipity, random screening of compounds etc. and rational methods like a thorough research into the disease leading finally to the selection of the suitable drug candidate, its synthesis and its screening. Newer methods include QSAR approach, combinatorial chemistry and molecular modeling. Marketing of a new drug can take place only after approval by FDA which requires substantial amount of documentation to procure investigational new drug (IND) approval, filing for new drug application (NDA), post marketing records and reports (phase IV studies) etc.
The process of investigation in designing and developing new compounds of biological interest has been made more necessary because of the emergence of new diseases caused by highly pathogenic microbes viz.; acquired immunodeficiency syndrome (AIDS) and severe acute respiratory syndrome (SARS) as well as frequent incidences of other life threatening diseases like dengue and encephalitis. Also, tremendous amount of research work has resulted in the introduction of effective and curative drugs in several health areas including AIDS and SARS. The life expectancy in India has increased because of definite advancement in this field. Until the end of nineteenth century, the useful life of a drug was considered to be 30 to 50 years but by the end of twentieth century it came down to one or two decades. This has resulted because of the strict regulations governing the development of new drugs that have evolved over last three decades, to assure their safety and efficacy. This article gives a brief account of the development of a new drug from its genesis, in the chemical laboratory, to its final acceptance as a safe and useful therapeutic agent.