Reversible Neutropenia With Olanzapine Following Clozapine-Induced Neutropenia

A 31-year-old Asian man with schizophrenia remained well for two years. He had been taking 20 mg of olanzapine, with no positive symptoms and minimal negative symptoms. Six months after the dose was gradually reduced, he developed a relapse of psychotic symptoms. He received sequential trials of risperidone (8 mg), olanzapine (30 mg), and a course of electroconvulsive therapy (because of severe agitation and suicidal and homicidal risks). During this period, his total white blood cell count ranged from 8,300/mm ³ to 10,200/mm ³ . As he remained symptomatic, a trial of clozapine was considered. A preclozapine laboratory test was unremarkable. While there was a significant reduction in psychotic symptoms, the patient’s total white blood cell count dropped to 2,100/mm ³, and he developed a chest infection in the fifth week of treatment. Clozapine was discontinued, and oral cephalosporins and quinolones were started. The patient’s physical condition improved, and his white blood cell count normalized to 7,900/mm ³ within 10 days. He was restarted on a regimen of olanzapine and remained hematologically stable during the subsequent 2 weeks, with white blood cell counts of 7,600/mm ³ and 7,900/mm ³ . However, during the third week after normal white blood cell counts, his cell count decreased again to 3,600/mm ³ and later to 3,200/mm ³ . Olanzapine was discontinued, and within a week the total white blood cell count rose to 10,100/mm ³ . Clinical history, physical examination, and laboratory tests did not show evidence of any other medical disorder.