Stereopsychopharmacology: past, present and future.

Stereoisomers have been used for more than a century to study the role of three-dimensional (spatial) features in biological processes. Configuration and conformation are spatial features of primary interest for effects of drugs. The role of configuration has been studied mainly by comparing effects of optical isomers (enantiomers), whereas the role of conformation has been investigated primarily using geometrical isomers and semi-rigid molecules. Spatial features have been shown to play a role in many effects of stereoisomers on noradrenergic, dopaminergic, serotonergic, cholinergic, opioid and GABAergic mechanisms. Further information on psychopharmacological effects of stereoisomers may lead to a better understanding of mental disorders and to improvements in drugs used to treat them.