Background: Over fifty percent of drugs being used clinically are chiral and 90% of them
are racemates. Unfortunately, they have both adverse and beneficial effects on body systems.
Methods: Because of the erratic effects of chiral compounds on body functional systems, literature
search was carried out with a view to identify CNS chiral drugs, their clinical advantages and disadvantages,
unique physicochemical properties and structural modifications into safer drugs.
Results: Findings have shown that majority of CNS and non-CNS acting drugs have chiral functional
groups that may occur as either dextrorotatory (clockwise) or levorotatory (anticlockwise) or racemates
which are inert. Sometimes, the enantiomers (optical isomers) could undergo keto-enol tautomerism,
appearing in either acidic or basic or inert form. Chiral CNS acting drugs have agonistic
and antagonistic effects, clinical advantages, disadvantages, and special clinical applications, possible
modifications for better therapeutic effects and possible synthesis of more potent drugs from
racemates. Clockwise chirality may be more effective and safer than the drugs with anticlockwise
chirality. When chiral drugs are in racemate state they become inert and may be safer than when they
are single. Also, diastereoisomers may be more dangerous than stereoisomers.
Conclusion: Therefore, chiral compounds should be adequately studied in lab rodents and primates,
and their mechanisms of actions should be comprehensively understood before being used in clinical
setting. Since many of them are toxic, their use should be based on principle of individualized medicine.
Their molecular weights, functional groups, metabolites, polymers and stereoisomers could be
valuable tools for their modifications.