Effectiveness of clozapine and olanzapine: a comparison in severe, psychotically ill patients.

New atypical antipsychotics have opened a new era in the treatment of schizophrenia owing to their effectiveness both on positive, but especially negative, symptoms, without extrapyramidal side-effects (Tandon et al., 1999). The archetypal atypical antipsychotic is clozapine, whose main side-effect is agranulocytosis. Recently, other new atypical antipsychotics have been developed, such as olanzapine (Stephenson and Pilowsky, 1999), which do not produce any adverse haematological effects (Beasley et al., 1997). Clozapine and olanzapine share lower D2 and D3 receptor affinity in the basal ganglia and nigrostriatal system, and higher affinity to muscarinic (M) and histaminergic (H) receptors than haloperidol. Moreover, clozapine has higher affinity to adrenergic (α1 and α2) receptors, while olanzapine has higher affinity to D2, D3, D4 and serotonergic (5-HT-2A) receptors (ratio 5-HT-2A/D2 > 2) (Coward, 1992). The pharmacological profile can explain the efficacy of these drugs not only on the positive, but also especially on the negative symptoms, representing the originality of new antipsychotic treatment. The improvement of primary negative symptoms (Crow, 1980) and the absence of secondary symptoms (produced by extrapyramidal side-effects) result in an increased compliance (Marder, 1998) and improvement of cognitive functions (insight capacity, self-awareness, judgement) (Meyer-Lindenberg et al., 1997). The aim of our study was to evaluate the effectiveness of clozapine and olanzapine in the treatment of schizophrenic patients in our psychiatric department. This is constituted by hospital wards connected to community services (outpatient care, semi-residential and residential centres for rehabilitative social programmes).