The application of the bioisosterism in lead optimization

The rational optimization of lead compounds into drug candidates is very important in the process of new drug development. Because a lead compound with a desired pharmacological activity may have associated with its drawbacks of pharmacology to promise the clinical usage, it is necessary to chemically modify the compounds to exclude such drawbacks by various approaches. The bioisosteric replacement represents a successful one. We herein review the principle of bioisosterism and some examples.