To evaluate the clinical benefit of switching to quetiapine sustained release (SR) in patients with schizophrenia experiencing suboptimal efficacy/tolerability with their current antipsychotic.

This was a 12-week, multicentre, open-label study (D1444C00147). Quetiapine SR (mg/day) was initiated during a 4-day cross titration phase (300 on Day 1; 600 on Day 2; 400, 600 or 800 on Day 3; flexible-dosing [400-800] from Days 4-84). Primary objective was to demonstrate that >50% of patients would achieve clinical benefit (improved CGI-Clinical Benefit [CB] score, based on CGI-I Efficacy index and tolerability burden) at Week 12. Secondary endpoints included CGI-I and PANSS total scores. Tolerability was assessed by adverse events (AEs), SAS and BARS scores. Mean changes in rating scale scores were analysed using ANCOVA.

477 patients were switched to quetiapine SR, 370 (77.6%) completed treatment. 295 of 470 evaluable patients (62.8%) achieved a clinical benefit upon switching to quetiapine SR (95% CI 58.4, 67.1, p<0.0001). Significant improvements were observed in mean [SD] change from baseline in CGI-CB (-2.1 [3.62]) and PANSS total (-13.6 [19.23]) (both p<0.001). Mean [SD] CGI-I score at endpoint was 2.8 [1.49] (p<0.001 for mean CGI-I<4). Common AEs included somnolence (17.8%), sedation (15.1%), dizziness and dry mouth (14.0% each). The incidence of EPS was 8.0%. Mean changes (improvements) from baseline in SAS and BARS scores were -2.1 and -0.4 respectively (both p<0.001).

Switching to quetiapine SR was associated with clinical benefit and was well tolerated in patients with schizophrenia experiencing suboptimal efficacy/tolerability with their previous antipsychotic treatment.