The QUARTZ ( Quetiapine Fumarate and Risperidone in the Treatment of Patients with Schizophrenia ) trial found that Quetiapine ( Seroquel ) presents similar levels of efficacy to Risperidone among schizophrenia patients completing an 8-week treatment course.
Quetiapine-treated patients showed a significantly lower rate of EPS ( extrapyramidal symptoms ), and mean prolactin levels were not raised from baseline.

The primary efficacy measure was change from baseline in Positive and Negative Syndrome Scale ( PANSS ) total scores; secondary outcomes included response rate ( > or = 40% reduction in PANSS scores ), Clinical Global Impression-Change ( CGI-C ), and cognitive and social functioning.

Patients were randomized to receive Quetiapine ( n=338 ) or Risperidone ( n=335 ). Flexible-dose regimens ( Quetiapine 200-800 mg/day, mean 525mg/day; Risperidone 2-8mg/day, mean 5.2mg/day ), based on existing product labels, allowed trial investigators to adjust doses based on patients' clinical response and tolerability. Patients who continued taking medication for the full eight-week period achieved greater improvement.

Improvements with Quetiapine and Risperidone were similar on PANSS total, PANSS response rates, CGI-C and cognitive function; around half the patients on each medicine discontinued before completing 8 weeks treatment ( 54.4% versus 49.9%, respectively ).

In the Quetiapine-treated group somnolence was more common ( 26% versus 20% ); rates of EPS were lower ( 13% versus 22% ); and prolactin levels were not elevated compared to baseline ( decrease of 11.5ng/mL on Quetiapine versus rise of 35.5ng/mL on Risperidone ).

Jeffrey Lieberman of Columbia University, who supervised the analysis and interpretation of the QUARTZ data, said, " In QUARTZ, Quetiapine had similar overall efficacy to Risperidone, and both treatments improved cognitive and social functioning, but tolerability profiles were different. Studies such as CATIE have shown that longer-term treatment adherence is related to both efficacy and tolerability. As physicians, effective care for patients with schizophrenia means choosing from a variety of medicines according to the needs of the individual patient."

The authors concluded “ Quetiapine and Risperidone had broadly comparable clinical efficacy. Both agents improved cognitive and social functioning, and neither had a clinically significant effect on weight or glucose. Somnolence was more common with Quetiapine; EPS and elevated prolactin rates were significantly higher with Risperidone. “

Source: Journal of Clinical Psychiatry, 2006


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