What is an atypical antipsychotic?

This is an exciting time for research into the drug treatment of schizophrenia. Modern techniques in imaging and molecular biology have contributed to our understanding of the receptor mechanisms of antipsychotic drug action. Several new antipsychotics are, or will shortly be, available and each of these new drugs promise improvements over classical antipsychotics. This review will discuss the concept of atypicality in antipsychotic drugs, and will describe some of the models for identification of improved antipsychotic action. The various receptor mechanisms proposed to underlie atypical antipsychotic action, several of which have featured in recent debates in this journal, will be considered in the light of the pharmacology of some of the newly-emerging antipsychotic drugs.