Chirality is a property of an object which is non-superimposable on its mirror image. The e word chiral stems from the Greek word “cheir”, which means 'handedness'. When an object cannot be superimposed on its mirror image, such a pair is referred to as chiral. It is just like the left and right hands. The two non-superimposable mirror-image twins of a chiral molecule is called enantiomers. The most commonly encountered stereogenic unit that confers chirality to drug molecules is stereogenic center. Stereogenic center can be due to the presence of tetrahedral tetra coordinate atoms (C,N,P) and pyramidal tricoordinate atoms (N,S). The word chiral describes the three-dimensional architecture of the molecule and does not reveal the stereochemical composition.
"From atoms to human beings, nature is asymmetric with respect to
chirality, or left- and right-handedness. Clues are beginning to emerge that connect chirality
on different levels" ...
"All life on Earth is made of molecules that twist in the same direction.
New research reveals that this may not always have been so" ...
"The mirror-image asymmetry of life is one of the biggest mysteries in biology" ...
Read more @ the following articles.
"Many medicinal agents important to life are combinations of mirror-image twins. Despite the
close resemblance of such twins, the differences in their biological properties can be profound.
In other words the component enantiomers of a racemic chiral drug may differ wildly in their
pharmacokinetic, pharmacodynamic profile. The tragedy of thalidomide illustrates the potential
for extreme consequences"...
Read more @ Wikipedia article links.
Links to some more publications in the area of drug chirality are given below. These articles and references therein might be of interest to readers.