Recombinant human granulocyte colony‐stimulating factor (rhG‐CSF; filgrastim) treatment of clozapine‐induced agranulocytosis

After 10 weeks of treatment with clozapine, severe agranulocytosis was diagnosed in a 33-year-old female. The patient was treated with filgrastim (granulocyte colony-stimulating factor [G-CSF]) 5 micrograms kg-1 day-1. The neutrophil count was 0.234 x 10(9) l-1 on admission, with a further decrease the next day to < 0.050 x 10(9) l-1, and this complete agranulocytosis continued for 10 days. As no response was obtained after 1 week the dosage of filgrastim was increased to 10 micrograms kg-1 day-1 with immediate improvement. A rapid and pronounced leucocytosis developed with maximal value of neutrophil granulocytes (including immature forms) of 33.108 x 10(9) l-1 on day 12 after admission. The patient only had minor infectious complications during the neutropenic period. In conclusion, early treatment with filgrastim seems warranted in severe cases of clozapine-induced agranulocytosis. A dosage of 10 micrograms kg-1 day-1 can be recommended.