Beginning with the introduction of chlorpromazine, the majority of antipsychotics brought forth in clinical development were products of D2 receptor screening programs. While strcturally diverse, this family demonstrated comparable efficacy and extrapyramidal side effects profiles. Clazapine, a compound introduced over 30 years ago, has catalyzed a new phase of antipsychotic drug research. The search for a profile of atypicality, e.g., efficacy in refractory patients and negative
symptomatology, reduced extrapyramidal side effects and minimal elevation of prolactin.. Despite clozapine's favourable efficacy and extrapyramidal tolerability pattern, its administration is subject to some limitations due to serious adverse effects, especially agranulocytosis.