To evaluate efficacy and tolerability of quetiapine sustained release (SR) in a 6-week study (D1444C00132).

588 patients with acute schizophrenia (PANSS total ≥70; CGI-S ≥4) were randomised to fixed-dose quetiapine SR 400, 600 or 800 mg/day (once-daily), quetiapine immediate release (IR) 400 mg/day (200 mg twice-daily; 5-day dose-escalation schedule), or placebo. Quetiapine SR doses: 400, 600 mg reached by Day 2; 800 mg by Day 3. Primary endpoint: change from baseline to Day 42 in PANSS total score (LOCF; ANCOVA). Other assessments: PANSS response rate (% patients with ≥30% reduction in total score from baseline); CGI-I response rate (% patients with rating ≤3); CGI-S; AEs.

446 patients (76%) completed the study (similar across groups). LS mean change from baseline in PANSS total score at Day 42 showed significant improvement versus placebo (-18.8): -24.8 (p=0.03), -30.9 (p<0.001), and -31.3 (p<0.001), quetiapine SR 400, 600, and 800 mg, respectively; -26.6 (p=0.004), quetiapine IR. Statistical separation from placebo at Day 42 for: change from baseline in CGI-S (quetiapine SR 600 and 800 mg; IR); PANSS and CGI-I response rates (all active treatments). Most common AEs with quetiapine: somnolence and dizziness. There were no unexpected AEs with quetiapine SR. Incidence of EPS-related AEs was similar to placebo. Two quetiapine SR and two IR patients discontinued due to AEs in Week 1.

Once-daily quetiapine SR (400-800 mg) was effective versus placebo in patients with acute schizophrenia. Rapid dose escalation was well tolerated, with a therapeutically effective dose reached by Day 2.