Olanzapine treatment after clozapine induced agranulocytosis

Clozapine is an atypical antipsychotic with a significant incidence of agranulocytosis. Olanzapine resembles clozapine structurally; however, it lacks a halogen, which has been implicated in agranulocytosis. Both agents have a similar pharmacological profile. We therefore studied olanzapine in patients with a history of clozapine-induced agranulocytosis. Two patients with severe clozapine-induced agranulocytosis and no benefit from classic neuroleptics were treated with olanzapine with informed consent. Psychosis improved in both patients and no hematological changes were noted. Olanzapine may be a safe treatment alternative in patients with a history of clozapine agranulocytosis.