The Efficacy and Tolerability of Once-Daily Extended Release Quetiapine Fumarate in Hospitalized Patients with Acute Schizophrenia: A 6-Week Randomized, Double-Blind, Placebo-Controlled Study

Objectives: This study aimed to demonstrate efficacy of once-daily extended release quetiapine fumarate (quetiapine XR) versus placebo in patients with acute schizophrenia. Methods: In this 6-week, randomized, double-blind study (5077IL/0041) patients were randomized to receive quetiapine XR (300, 600, or 800 mg/day), quetiapine fumarate immediate release (quetiapine IR) [300 or 600 mg/day], or placebo. Primary endpoint was change from baseline in the Positive and Negative Syndrome Scale (PANSS) total score at Day 42. Secondary variables included PANSS response rate at Day 42 (30% decrease in PANSS total score from baseline) and Clinical Global Impressions Severity (CGI-S) and Improvement (CGI-I) ratings. Safety assessments included adverse event (AE) reporting and laboratory measures. Results: Of 532 patients randomized, 222 (41.7%) completed the study. Improvements in PANSS total scores from baseline to Day 42 across treatment groups were: quetiapine XR 300 mg/day 5.01, 600 mg/day 13.01 and 800 mg/day 11.17, quetiapine IR 300 mg/day 9.42 and 600 mg/day 6.97, and placebo 5.19; the difference in change was statistically significant only for quetiapine XR 600 mg/day (p 0.033). There were no statistically significant differences between active treatment groups and placebo for PANSS response rates. Several post hoc analyses were conducted to explain the study efficacy outcome but these were inconclusive. Quetiapine XR was generally well tolerated with the majority of AEs being mild or moderate in intensity and no unexpected AEs. Conclusions: Superior