Rechallenge with clozapine following leucopenia or neutropenia during previous therapy

Abstract

Background: Further treatment with clozapine is contraindicated in any patient who has previously experienced leucopenia or neutropenia during clozapine therapy. Aims: To investigate the results of such a rechallenge in 53 patients. Method: An analysis was made of the demographic, haematological and outcome data of patients in the UK and Ireland who were rechallenged with clozapine following leucopenia or neutropenia during previous clozapine therapy. Results: Of 53 patients who were rechallenged, 20 (38%) experienced a further blood dyscrasia. In 17 of these 20 patients (85%) the second blood dyscrasia was more severe (P < 0.001), in 12 (60%) it lasted longer (P=0.0368) and in 17 (85%) it occurred more quickly on rechallenge (P < 0.001). Of the original 53 patients, 55% (29 patients) are still receiving clozapine. Conclusions: No clear risk factor for repeat blood dyscrasias was identified. Despite this, after risks and benefits have been considered, rechallenge may well be justified in some patients.