Selective drugs, activity toward receptors

Currently there is a trend toward the synthesis and large-scale production of a single active enantiomer in the pharmaceutical industry [61-63]. In addition, in some cases a racemic drug formulation may contain an enantiomer that will be more potent (pharmacologically active) than the other enantiomer(s). For example, carvedilol, a drug that interacts with adrenoceptors, has one chiral center yielding two enantiomers. The (-)-enantiomer is a potent beta-receptor blocker while the (-i-)-enantiomer is about 100-fold weaker at the beta-receptor. Ketamine is an intravenous anesthetic where the (+)-enantiomer is more potent and less toxic than the (-)-enantiomer. Furthermore, the possibility of in vivo chiral inversion—that is, prochiral chiral, chiral nonchiral, chiral diastereoisomer, and chiral chiral transformations—could create critical issues in the interpretation of the metabolism and pharmacokinetics of the drug. Therefore, selective analytical methods for separations of enantionmers and diastereomers, where applicable, are inherently important. 

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