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Motor and Sexual Side Effects More Likely With Risperidone Than Quetiapine: Presented at APA

By Roberta Friedman, PhD

SAN FRANCISCO, CA -- May 23, 2003 -- Patients with schizophrenia respond equally well to treatment with either quetiapine or risperidone, but those on risperidone appear to be nearly twice as likely to have motor and sexual problems.

These findings were presented here May 21^st at the 2003 Annual Meeting of the American Psychiatric Association.

Xue Zhong, MD, of AstraZeneca, in Wilmington, Delaware, United States, presented a poster detailing the responses of 328 patients who were randomized to quetiapine and 320 to risperidone. The study followed treated patients for 8 weeks.

Mean daily doses were 480 mg (range 200-800 mg) for quetiapine and 5.2 mg (range 2-8 mg) for risperidone. Dosing was flexible, and the drugs were given twice per day.

Investigators compared end point scores on the Positive and Negative Syndrome Scale (PANSS) to baseline scores on this measure of positive and negative symptoms of the disease.

Each group showed about a 40% rate of response, with ratings of "much improved " or "very much improved." A quarter of each group showed at least a 30% reduction in the PANSS total score. But 21.9% of patients taking risperidone had adverse events involving extrapyramidal symptoms, compared with only 12.7% of patients using quetiapine. No differences appeared in glucose levels or weight of the patients between the 2 groups.

Several meeting attendees remarked on the increase in prolactin levels produced by risperidone. Normal levels are 12 to 20 ng/mL, but risperidone increased prolactin well above this range.

Dr. Zhong responded that risperidone is known to raise prolactin levels, and, as a result, incurs infertility in both genders. Women cease menstruating and men experience breast enlargement and may even lactate. Haloperidol also causes these prolactin-mediated adverse effects, he noted.

The study was funded by AstraZeneca Pharmaceuticals.


[Study title: A Comparison of the Efficacy and Safety of Quetiapine and Risperidone. Abstract NR530]

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