quetiapine and clozapine. In summary, as mentioned earlier, it appears to be prudent to monitor white blood cell counts in patients being treated with atypical antipsychotic drugs and who have a history of drug-induced white blood cell count disorders, as well as in patients who are treated with other drugs that bring a risk of white blood cell aberrations.
Conley and Mahmoud  reported a study of 377 patients with schizophrenia or schizo-affective disorder who were randomized to double-blind treatment with risperidone or olanzapine for 8 weeks. The mean (sd) doses were 12.4 mg/day for olanzapine and 4.8 mg/day for risperidone; 77.2% of the olanzapine-treated patients and 71.8% of the risperidone-treated patients completed the study. Both treatments produced significant symptom reductions; these did not differ in an end-point analysis but did at week 8, favouring risperidone on positive symptoms and anxiety/depression factors on the PANSS. EPS symptoms were comparable between treatments, but olanzapine was associated with more weight gain.
As noted earlier, Volavka et al.  reported the results of a 14-week, randomized double-blind trial comparing clozapine, olanzapine, risperidone and haloperidol in 157 partially responsive but residually symptomatic patients with schizophrenia. They found that the three SGAMs produced statistically significant reductions in symptoms from baseline, while haloperidol did not, but only clozapine and olanzapine were significantly better than haloperidol. However, the doses of olanzapine and risperidone were higher than usual (olanzapine mean, 30.4 mg/day; risperidone men, 11.4 mg/day). Although the greater efficacy of the SGAMs was statistically significant, it was clinically modest. EPSs were more common in haloperidol-treated and risperidone-treated patients, and weight gain was greater with clozapine and olanzapine treatment. Using data from the same study, Citrome et al.  examined treatment effects on aggressive behavior. They found that clozapine was significantly more effective in reducing hostility and aggression than haloperidol, while olanzapine and risperidone were not.
Csernansky et al. examined the efficacy of risperidone and haloperidol in preventing relapse for a minimum of 1year in 397 patients with schizophrenia or schizo-affective disorder in a randomized double-blind trial. The risk of relapse was significantly lower in risperidone-treated patients (34%) than in haloperidol patients (60%). Risperidone also produced fewer EPSs than haloperidol.
An open comparison of quetiapine (mean daily dose 253,9 mg) and risperidone (4.4 mg) confirmed previous findings of quetiapine's 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 anticholi- nergic 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.