The first edition of this book contained the observation that the stereo- isomeric composition of drug substances was rapidly becoming a key issue
in the development, approval, and clinical use of pharmaceuticals. During
the past four years, this assertion has become a reality, and stereochemis-
try is now a major theme in all branches of pharmaceutical science. The
interest in this topic is reflected in the content of articles appearing in
natural and biological science journals and two new international journals,
Chirality and Tetrah£dron Asymmetry. Moreove a variety of conferences
and courses have been devoted to this subject. In addition, the European,
North American, and Japanese drug regulatory agencies have expressed
an interest in a closer examination of the stereoisomeric composition of
chiral drugs and the therapeutic and toxicological consequences of this
composition. The pharmaceutical industry has quickly responded to this
situation by considering stereochemistry in its initial drug evaluation
strategies. In fact, at the present time, a number of companies have made
the decision to market only single-isomer drugs.