Abstract
Almost all current research into developing new pharmacological treatment for depression and schizophrenia is focused directly on modulating neurotransmitter receptors in the brain. This approach was stimulated by the chance discovery of the prototype psychotropic drugs such as chlorpromazine and imipramine and the subsequent development of hypotheses based on the presumed mode of action of these drugs. Even clozapine was first introduced as yet another dopamine receptor blocker, and it was only after it was recognised that clozapine shows improved efficacy that hypotheses were developed as to its possible mode of action. Subsequent research based on the receptor approach has led to improved side-effect profiles for modern psychotropic agents, but has not resulted in any improvement of efficacy over and above that of the drugs discovered by good fortune rather than by hypotheses.