Filgrastim treatment of three patients with clozapine-induced agranulocytosis.

BACKGROUND

Agranulocytosis is the most serious side effect of clozapine therapy, occurring in approximately 1% of all treated patients. Despite careful blood monitoring, a significant number of cases of agranulocytosis and resulting fatalities have occurred. Strategies are needed to manage clozapine-induced agranulocytosis more safely.

METHOD

This report describes the management of three state hospital inpatients who developed clozapine-induced agranulocytosis. All patients were diagnosed as having chronic paranoid schizophrenia according to DSM-III-R criteria and had previously failed to respond to treatment with standard antipsychotic medications. After onset of agranulocytosis, all patients were transferred to a medical service in a university hospital and treated with recombinant granulocyte colony-stimulating factor (filgrastim).

RESULTS

White blood count and absolute neutrophil count returned to within normal limits in each patient after 5 to 8 days of treatment with filgrastim 300 micrograms/day subcutaneously. No side effects were observed during filgrastim treatment.

CONCLUSION

Treatment with filgrastim appears to be safe and effective in decreasing the duration of clozapine-induced agranulocytosis. While further studies are necessary to establish the safety and effectiveness of this treatment, filgrastim should presently be considered a treatment of choice for clozapine-induced agranulocytosis.