<prompt> Which one of the following antipsychotic drugs is considered the best in treatment of Resistant Schizophrenia?OlanzapineClozapineResperidoneChlorpromazine  <response>: B Clozapine Clozapine appears to be most effective of atypical members. Its main side effects are: Agranulocytosis, Seizures, Hyperthermia Its side effects profile make it appropriate for treatment of resistant cases. Olanzapine Is chemically similar to clozapine but of leaves efficacy and causes rapid wt gain. Risperidone - benzisoxazole: It is 5HT, D2 and a-2 antagonist Its a-2 antagonism contribute to its ability to improve mood and increase motor activity Chlorpromazine - Its is typical antipsychotic anticholinergic highly sedative Clozapine appears to be the most effective member of this class and has demonstrated superiority to other atypical agents in preventing suicide;however, its side-effect profile makes it most appropriate for treatment resistant cases Olanzapine is similar neurochemically to clozapine but has a significant risk of inducing weight gain. Risperidone, a benzisoxazole derivative, is more potent at 5HT2 than D2 receptor sites, like clozapine, but it also exerts significant antagonism, a property that may contribute to its perceived ability to improve mood and increase motor activity. Risperidone is not as effective as clozapine in treatment resistant cases but does not carry a risk of blood dyscrasias. chlorpromazine and thioridazine, are more sedating and anticholinergic and more likely to cause orthostatic hypotension. 