56 下列何種抗精神病藥物最可能導致顆粒性白血球減少（agranulocytosis）？

chlorpromazine clozapine perphenazine haloperidol

clozapine: AGRANULOCYTOSIS!!!!!!

The first of the atypical antipsychotics to be developed, it was first introduced in Europe in 1971, but was voluntarily withdrawn by the manufacturer in 1975 after it was shown to cause agranulocytosis, a condition involving a dangerous decrease in the number of white blood cells, that led to death in some patients. In 1989, after studies demonstrated that it was more effective than any other antipsychotic for treating schizophrenia, the U.S. Food and Drug Administration (FDA) approved clozapine's use but only for treatment-resistant schizophrenia. The FDA requires blood testing for patients taking clozapine.^[1][2] The FDA also requires clozapine to carry five black box warnings for agranulocytosis, seizures, myocarditis, for "other adverse cardiovascular and respiratory effects", and for "increased mortality in elderly patients with dementia-related psychosis."^[3] In 2002 the FDA approved clozapine for reducing the risk ofsuicidal behavior for patients with schizophrenia.