Reversible neutropenia during treatment with olanzapine: three case reports.

Olanzapine is an atypical antipsychotic with a low incidence of extrapyramidal-motoric side effects. Its chemical structure is related to clozapine, which is known to induce neutropenia in up to 3% and agranulocytosis in approximately 1% of patients. It has been discussed controversially whether olanzapine also has a potential to induce neutropenia and agranulocytosis. Up to now, seven case reports of haematopoetic disturbances during olanzapine treatment have been published, including one case of olanzapine-induced agranulocytosis (Naumann et al. 1999), two cases of neutropenia (Steinwachs et al. 1999) and one leucopenia (Meissner et al. 1999). We report three subjects with reversible neutropenia under olanzapine, with rapid normalisation of neutrophil cell counts after discontinuation of olanzapine. In one case neutropenia occurred after administration of a single dose of olanzapine, in another case after 6 weeks of treatment. In both cases, patients had no clinical complications. In the third case, neutropenia appeared after 1.5 years of treatment followed by development of pneumonia. Two cases were recorded within the German drug surveillance project (AMSP); the third case was observed in a randomised, double-blind, multicentre study comparing olanzapine with clozapine.