Neutropenia and agranulocytosis in patients receiving clozapine in the UK and Ireland.
BACKGROUND
Clozapine can cause reversible agranulocytosis and neutropenia. This study documents the occurrence of blood dyscrasias and identifies predisposing risk factors.


METHODS
An analysis was made of the haematological, demographic, and dosage data from a central database on 6316 patients receiving clozapine over four and a half years in the UK and Ireland.


RESULTS
During the study period, 2.9% of the patients developed neutropenia and 0.8% developed agranulocytosis. The peak incidence of both disorders was in the first 6-18 weeks of treatment. Fatal agranulocytosis occurred in 0.03% of patients. After the first year of treatment, the incidence of agranulocytosis significantly decreased to the order noted with some phenothiazines.


CONCLUSIONS
The use of a patient monitoring service kept the haematological risks associated with using clozapine within acceptable limits, particularly in view of the benefits of this medication in treatment-resistant schizophrenia.
Clozaril Patient Monitoring Service, Sandoz Pharmaceuticals, Frimley, Surrey.
K
K
Atkin
F
F
Kendall
D
D
Gould
H
H
Freeman
J
J
Liberman
D
D
O'Sullivan
D000328:Adult; D016907:Adverse Drug Reaction Reporting Systems; D000368:Aged; D000380:Agranulocytosis / Q000139:chemically induced*; D014150:Antipsychotic Agents / Q000009:adverse effects* / Q000627:therapeutic use; D003024:Clozapine / Q000009:adverse effects* / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007494:Ireland; D008297:Male; D008875:Middle Aged; D009503:Neutropenia / Q000139:chemically induced*; D012307:Risk Factors; D012559:Schizophrenia / Q000188:drug therapy*; D006113:United Kingdom
D014150:Antipsychotic Agents; D003024:Clozapine