ABSTRACT
Despite the amount of research conducted in pharmaceutical companies, the success rate for the lead molecule to reach into market is markedly low and though there are many new techniques for drug designing such as combinatorial chemistry, high throughput screening, they don’t seem to have a higher significance in drug discovery. This is most likely due to our limited understanding of what turns a good lead compound into potential drug candidate. The problem is also featured by the fact that most recently launched drugs 106are not only derived by modifications of known drug structures or published lead structures, but are also even closely related to their original lead compounds (Bodor and Buchwald, 2008). The significance of drug design would only be fulfilled not only after increased activity, but also therapeutic index, margin of safety (TI = TD50/ED50, ratio between median toxic and median effective dose) and degree of selectivity.
