Leucopenia induced by low dose clozapine in Parkinson's disease recedes shortly after drug withdrawal. Clinical case descriptions with commentary on switch-over to olanzapine

Four patients affected by severe Parkinson's disease developed leucopenia ( 900-1200 WBC) during treatment of psychosis (3) or untreatable insomnia (1) with clozapine (37.5-75 mg/day). Clozapine withdrawal was followed by reco very of leucopenia (4000-6000 WBC) in two weeks with no need for the admini stration of leucokines. After 1-6 months olanzapine was administered (incre asing the dose from 2.5 to 10 mg/day) to treat persisting disturbances, but the drug induced severe worsening of parkinsonism and also this drug had t o be withdrawn.