Preclinical findings with new antipsychotic agents: what makes them atypical?

Many early antipsychotics such as haloperidol, while effective in treating the symptoms of schizophrenia, cause detrimental side effects and moreover induce nonspecific sedation in many patients. Newer drugs such as remoxipride are as effective as the classical antipsychotics but induce fewer debilitating side effects. These clinical properties are reflected to some extent in their preclinical pharmacology, with drugs such as remoxipride having effects on various preclinical behavioural and biochemical models that are quite different to those exerted by drugs such as haloperidol. This article reports some new behavioural data and discusses the various mechanisms that can underlie the effect of new atypical antipsychotics.