What makes an antipsychotic 'atypical'? Conserving the definition

Current usage of the term 'atypical' in relation to antipsychotics lacks clear theoretical underpinnings and rigour in application. The prevailing definition of atypicality is a reduced liability to induce extrapyramidal side effects (EPS). However, this definition appears incomplete in the face of numerous other limitations associated with antipsychotics that can impact adversely on patient wells being; these encompass issues of efficacy, non-motoric physiology and quality of life. On this basis, more conservative, operationalised criteria for atypical anti psychotic activity can be offered and applied to representative classical versus more recently introduced antipsychotics. These criteria include a reduced liability to induce EPS, but also superior efficacy, efficacy in patients who do not respond to classical antipsychotics, and no induction of subjective dysphoria, sedation, autonomic/cardiac effects, sexual dysfunction and bodyweight gain, and no elevation of prolactin levels or other endocrine effects. Such criteria codify yet higher aspirations fur treatment with the welcome array of newer agents that is currently emerging.