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Evaluation of the feasibility of switching from immediate release quetiapine to extended release quetiapine fumarate in stable outpatients with schizophrenia

Möller, Hans-Jürgena; Johnson, Sunnyb; Mateva, Temenuzhkac; Brecher, Martind; Svensson, Olae; Miller, Franke; Meulien, Didiereon behalf of the Study 146 investigators

International Clinical Psychopharmacology: March 2008 - Volume 23 - Issue 2 - p 95-105
doi: 10.1097/YIC.0b013e3282f2d42c

This double-blind, double-dummy study (D1444C00146) evaluated the efficacy and safety of switching patients with clinically stable schizophrenia from quetiapine immediate release (IR) to the same dose of once-daily extended release quetiapine fumarate (quetiapine XR). Patients received quetiapine IR 400–800 mg/day twice daily for 4 weeks, and were then randomized (2 : 1) to a once-daily equivalent dose of quetiapine XR or maintained on IR for 6 weeks. The primary variable was the proportion of patients who discontinued treatment owing to lack of efficacy or whose Positive and Negative Syndrome Scale scores increased by at least 20% from randomization to any visit. In total, 497 patients were randomized to quetiapine XR (n=331) or IR (n=166). Noninferiority (6% margin; one-sided test, 2.5% significance level) was narrowly missed for the primary efficacy variable for the modified intention-to-treat population (9.1%, quetiapine XR; 7.2%, quetiapine IR; difference 1.86%; 95% confidence interval: −3.78, 6.57; P=0.0431), but was shown for the per-protocol population (5.3%, quetiapine XR; 6.2%, quetiapine IR; difference: −0.83%; 95% confidence interval: −6.75, 3.71; P=0.0017). Serious adverse event incidence was low for quetiapine XR and IR; there were no unexpected adverse events. In conclusion, efficacy was maintained without compromising safety/tolerability when switching patients with stable schizophrenia from twice-daily quetiapine IR to once-daily quetiapine XR (400–800 mg/day).

aPsychiatric Hospital of the University of Munich, Munich, Germany

bCredit Valley Hospital, Mississauga, Ontario, Canada

cDistrict Dispensary for Psychiatric Disorders, Rousse, Bulgaria

dAstraZeneca Pharmaceuticals, Wilmington, Delaware, USA

eAstraZeneca R&D, Södertälje, Sweden

Correspondence to Prof Hans-Jürgen Möller, MD, Psychiatric Hospital of the University of Munich, Nussbaumstr. 7, 80336 Munich, Germany

Tel: +49 89 5160 5501; fax: +49 89 5160 5522; e-mail:

Received 2 March 2007 Accepted 1 October 2007

© 2008 Lippincott Williams & Wilkins, Inc.