Copolov et al.  examined quetiapine and haloperidol in a multicentre, international, 6-week, randomized controlled trial (RCT) study of patients with acute exacerbations of schizophrenia. They found comparable reductions in psychopathology with the two drugs, but fewer side-effects (in terms of EPS and prolactin elevations) with quetiapine.
Emsley et al.  compared the effects of quetiapine and haloperidol in partially responsive patients with schizophrenia in an 8-week RCT. They reported a superior response for quetiapine-treated patients on PANSS and Brief Psychiatric Rating Scale scores, but this did not reach statistical significance. In addition, quetiapine-treated patients had fewer EPSs and less elevation of prolactin than haloperidol-treated patients.
An open comparison of quetiapine (mean daily dose 253,9 mg) and risperidone (4.4 mg) confirmed previous findings in which quetiapine showed good tolerability with regard to EPSs . Approximately half of the patients suffering from schizophrenia or other disorders had EPSs at baseline. Motor side-effects declined to a similar degree over the course of the 4-month open trial in both groups, but quetiapine-treated patients required less anticholinergic medication than patients in the risperidone group. Somnolence was the most common adverse event in both groups, though it occurred at a significantly higher rate in the quetiapine group. Dry mouth and dizziness were also more common in patients treated with quetiapine.
The favourable EPS profile of quetiapine has also been found in patients with Parkinson's disease who experienced psychosis. A number of small clinical trials have consistently shown that quetiapine improved psychosis in these patients without worsening motor functions; as a result, quetiapine is now a preferred treatment for this clinical occurrence .
Whether or not quetiapine induces weight gain is still a contentious issue: while Mullen et al. and Brecher et al.  have not found this to be a problem, Wetterling et al. , in a recent review, noted that a weight gain of 1.8 kg/month is to be expected under short-term treatment with quetiapine. In this context, it is of interest that two children successfully treated with quetiapine for Tourette’s Syndrome  showed substantial weight loss while being treated with quetiapine. On the other hand, Shaw et al. , who studied the efficacy and tolerability of quetiapine in 15 psychiatric adolescents, found a weight gain of 3.4 kg (corrected for expected weight gain) over the 8-week period.
Two groups have presented case reports on neutropenia and agranulocytosis, respectively, linked to quetiapine treatment [54,55]. Interestingly, two of the three patients reported by Ruhe et al.  had a history of clozapine-induced agranulocytosis. Only two out of four patients in these reports were on quetiapine monotherapy; the other two received combination treatments of quetiapine with olanzapine and lithium, or quetiapine with flupenthixol decanoate. Ruhe et al.  also cite a number of other cases of agranulocytosis or granulocytopenia associated with quetiapine that were reported to the Uppsala Monitoring Center of the World Health Organization. While they note that these data have to be interpreted with caution, they point to the structural similarity between