5-HT(3) receptor antagonists.

The 5-HT(3) receptor is a ligand-gated ion channel widely distributed in the central and peripheral nervous systems. Many selective 5-HT(3) receptor antagonists have been developed; animal studies with such compounds suggested their potential therapeutic value in combating emesis and a wide range of CNS diseases including anxiety, schizophrenia, drug dependence and Alzheimer's disease. Their successful introduction as anti-emetics, with irritable bowel syndrome emerging as a further indication have partially fulfilled this initial promise. However, the CNS area has been less productive and, to date, no selective 5-HT(3) receptor antagonist has been approved for use in a CNS disease.