Medicinal chemists are able to synthesize a vast number of compounds in a relatively short time, a process referred to as combinatorial chemistry where one part of a molecule is maintained, as different chemical groups are attached to its molecular framework to produce a series of similar molecules with distinct structural variations and every molecule is tested for its biological activity.

The small molecule with biological activity is often called as “hits”, can be synthesized from a milligram to a gram scale. These hits are different in the forms of radiolabeled, stable-labeled, active pharmaceutical ingredients and metabolites and analogs.

Compounds can be used on two important design strategies:

Diversity oriented design: The goal is to generate libraries with a highly diverse set of chemical compounds like skeletal diversity, electro-statics or molecular properties like hydrogen bond donors/acceptors, polarizable groups, charge distributions, hydrophobic and lipophobic fragments

Target oriented design: It creates libraries that are focused around specific chemotypes, molecular species, or classes of compounds.