Why QSAR and Molecular Modeling

10 gtoiq)s for esterification 10 gratis for aliphatic C 10 groups for ring N =50 x 10x10x10 = 312.5 billion analogs 

The astronomical cost of new drug discovery is fueled primarily by two factors (a) Combinatoric explosion in the number of possible derivatives of a lead, and (b) Cost of the screening process. A chemical can be screened by three methods in vivo, in vitro, and finally in silico. The potential therapeutic activity and toxicity of a chemical have usually been assessed in the pharmacological literature using a set of physicochemical properties and bioassay results. Table 1 gives a partial and ever expanding list of such properties. 

Additionally, the Hiunan Genome Project has catapulted us into the era of omics sciences, represented by genomics, proteomics, and metabolomics. Data from these sciences are thought to be useful in pharmaceutical drug design [9-12]. 

While in vivo and in vitro bioassays are costly, even experimental physicochemical properties such as those listed in Table 1 could be costly if the number of compounds to be evaluated is very large. That is why the recent trend 

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