To assess the safety and tolerability of quetiapine XR using pooled data from 3 studies (5077IL/0041, D1444C00132, D1444C00133).

Quetiapine XR (300mg [1 study], 400mg [2 studies], 600mg or 800mg once daily) was evaluated in 3 similarly designed, 6-week, placebo-controlled, double-blind, randomised studies in patients with acute schizophrenia. Matched dose quetiapine IR was included to demonstrate assay sensitivity. Safety assessments included AEs and vital signs.

The pooled safety population included 1684 patients (951, quetiapine XR; 414, quetiapine IR; 319, placebo). Mean (SD) duration of exposure to quetiapine XR, quetiapine IR and placebo was 31.8 (14.9), 29.4 (15.9) and 30.6 (15.6) days, respectively.

The percentage of patients reporting an AE was similar for quetiapine XR (69.5%), quetiapine IR (72.5%) and placebo (61.4%). Serious AE incidence was similar for quetiapine XR (4.4%), quetiapine IR (3.9%) and placebo (4.4%). 6.4%, 7.7% and 7.5% of patients receiving quetiapine XR, quetiapine IR and placebo discontinued owing to AEs, respectively.

The five most common drug-related AEs (≥5%) were: sedation (11.5%, 14.0%, 5.0%), somnolence (10.6%, 11.4%, 3.1%), dry mouth (10.4%, 8.0%, 1.3%), dizziness (7.5%, 6.8%, 3.1%) and orthostatic hypertension (5.8%, 7.5%, 3.8%), for quetiapine XR, quetiapine IR and placebo, respectively. There was no dose relationship with any common AE for quetiapine XR. For completers, mean weight increases were: quetiapine XR (n=555), 1.77kg; quetiapine IR (n=215), 2.19kg; placebo (n=163), 0.26kg.

Once-daily quetiapine XR (300-800mg/day) was well tolerated in patients with acute schizophrenia. The tolerability profile was consistent with the known safety profile for quetiapine IR.