Olanzapine (Zyprexa): increased incidence of cerebrovascular events in dementia trials

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Abstract
The drug: Olanzapine is an antipsychotic agent with a novel mechanism of action. The US Food and Drug Administration recently issued a warning about an increased incidence of hyperglycemia and diabetes among patients taking the drug.3 In a separate letter to physicians, Eli Lilly Canada also recently reported some summary data on cerebrovascular event rates in 5 placebo-controlled trials of olanzapine in elderly patients (ages not specified) who had dementia (including Alzheimer's, vascular dementia and mixed dementia) (Table 1).4 According to information supplied by the manufacturer, only 2 of the 5 studies have been published in full (Table 1). The duration of the published trials was between 6 and 10 weeks, with doses of the drug ranging from 1 to 15 mg. Overall, the relative risk of a cerebrovascular event among patients taking olanzapine in the 5 trials was 3.1 (95% confidence interval [CI] 0.7– 13.5) and the absolute increased risk was 0.9%. The rates of cerebrovascular events were similar to those reported for risperidone.2