Olanzapine: new preparation. Keep an eye on this neuroleptic.

(1) Olanzapine, a neuroleptic, has obtained European marketing authorisation for the treatment of schizophrenia. (2) The clinical file is satisfactory, but in the absence of relevant trials it has not yet been demonstrated that olanzapine has a specific activity on the positive or negative symptoms of schizophrenia. (3) The global efficacy of olanzapine was not significantly different from that of haloperidol in two of the three comparative trials published to date. (4) The only relevant comparative trial fails to demonstrate the superiority of olanzapine over risperidone. (5) Olanzapine has fewer adverse neurological effects than haloperidol, but there is no evidence that it differs from other recent neuroleptics in this respect. (6) Olanzapine can have anticholinergic adverse effects and frequently causes weight gain. (7) Active pharmacovigilance is required, as subclinical cases of elevated transaminase levels, increased blood pressure and QT prolongation were observed in clinical trials (2,500 patients treated).