Real Life Medicine 5-4 Chiral Drugs—Racemic or Enantiomerically Pure

REAL LIFE MEDICINE 5-4 Chiral Drugs—Racemic or Enantiomerically Pure  

Until the early 1990s, most synthetic chiral medicines were prepared as racemic mixtures and sold as such. The reasons were mainly of a practical nature. Reactions that convert an achiral into a chiral molecule ordinarily produce racemates (Section 5-7). In addition, often both enantiomCTs have comparable physiological activity or one of them (the wrong one) is inactive therefore resolution was deemed unnecessary. Finally, resolution of racemates on a large scale is expensive and adds substantially to the cost of drug development. 

HowevCT, in a number of cases, one of the enantiomers of a drug has been found to act as a blocker of the biological receptor site, thus diminishing the activity of the other enantiomer. Worse, one of the enantiomers may have a completely different, and sometimes toxic, spectrum of activity. This phenomenon is quite general, since nature s receptor sites are handed (Real Life 5-5). Several examples of diffoent bioactive behavior between enantiomers are shown below. 

In 1806, asparagine was the first amino acid to be isolated from nature, from the juice of asparagus. 

Japan Professor K. Barry Sharpless (b. 1941), The Scripps Research Institute, La Jolla, California. 

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