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Antipsychotic dosing for schizophrenia

Vol. 3, No. 10 / October 2004

Dr. Willem Martens’ article, “Recovery from Schizophrenia: Fact or Fiction” (Current Psychiatry, July 2004), presents inaccurate and misleading information about quetiapine dosing during recovery.

Although quetiapine dosing during schizophrenia’s maintenance phase has not been systematically addressed in blinded studies, Buckley 1 presented results from open-label extensions to three 6-week, double-blind, randomized trials of quetiapine in patients with schizophrenia. During these extension periods, which averaged 36 months, clinicians were encouraged to adjust the dosage to optimize efficacy and tolerability. The mean quetiapine dosage during these periods was 439 mg/d, and mean Brief Psychiatric Rating Scale scores continued to decline (13.94 to 9.04).

These findings suggest that patients who continued to do well on quetiapine did so on dosages similar to initial acute dosing. This information is critical to preventing relapse and providing longterm benefits to patients taking quetiapine.

Jeffrey M. Goldstein, PhD
Director clinical science

Wayne Macfadden, MD
U.S. medical director, Seroquel
AstraZeneca LP, Wilmington, DE


  1. Buckley PF. Maintenance treatment for schizophrenia with quetiapine. Hum Psychopharmacol 2004;19:121–4.

In “Recovery from Schizophrenia: Fact or Fiction,” the dosage range for risperidone cited in Table 3 does not reflect oral risperidone dosing.

The Dosing and Administration section of the U.S. Risperdal tablets/oral solution package insert states: “Efficacy in schizophrenia was demonstrated (at) 4 to 16 mg/d…however, maximal effect was generally seen (at) 4 to 8 mg/d.” Dosages >6 mg/d bid were not shown to be “more efficacious than lower doses, were associated with more extrapyramidal symptoms and other adverse effects, and are not generally recommended.”

Recommended dosing for risperidone long-acting IM injection—as stated in the package insert—is 25 mg every 2 weeks. The insert’s U.S. Dosing and Administration section further states: “Although dose response for effectiveness has not been established, some patients not responding to 25 mg may benefit from…37.5 mg or 50 mg. (The) dose should not exceed 50 mg every 2 weeks.”

Also, the listing of potential antipsychotic side effects in Table 3 does not reflect side effects reported in the current literature, clinical trials involving risperidone, or the U.S. prescribing information for risperidone oral and IM formulations. Clinicians should refer to these package inserts.

The 2004 American Psychiatric Association “Practice Guidelines for the Treatment of Patients with Schizophrenia” also addresses side effects and dosing guidelines for atypical antipsychotics, including risperidone. To obtain this resource, visit guide.cfm.

Patricia A. Wilkinson, PharmD, MS, BCPP
Associate director, medical services
Janssen Medical Affairs, LLC,
Titusville, NJ

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