Do single enantiomers have something special to offer?

Single enantiomers have a significant role to play in enhancing drug discovery and development. Researchers are overcoming the technical limitations associated with developing single enantiomers, and the growth in targeted drug development already means that more single enantiomers are developed ab initio. Moreover, as pharmaceutical companies decide whether to progress a single enantiomer, rather than a racemate, early in development, increasingly fewer racemates will reach the market. Developing a single enantiomer as a line extension of a profitable drug is of growing importance and is reflected in the increasing number of speculative patents on chiral switches. The implications are that single enantiomers will eventually touch every area of clinical medicine. As the number of chiral drugs launched onto the market increases, so clinicians need to be aware of the key issues surrounding enantiomers. This review examines some of the issues arising from the growing importance of enantiomers in medicine.