Abstract

Quetiapine is an atypical antipsychotic agent with well established efficacy and tolerability in the acute and maintenance treatment of adults with schizophrenia. The extended-release formulation of quetiapine (quetiapine XR) was developed to provide more convenient once-daily administration, as well as allowing simple and rapid dose escalation, with the aim of improving compliance (known to be a substantial issue in patients with schizophrenia). In several short-term clinical trials, oral quetiapine XR 400-800 mg once daily was generally effective across a range of symptoms in the acute treatment of schizophrenia. As a long-term maintenance treatment, quetiapine XR prevented relapse in patients with stable disease, with significantly longer times to relapse in patients treated with quetiapine XR compared with placebo. Quetiapine XR was generally well tolerated in clinical trials. According to pooled results from three 6-week trials, events occurring in >or=5% of quetiapine XR recipients with an incidence>or=2-fold that seen in placebo recipients were dry mouth, somnolence and dizziness. A generally low incidence of extrapyramidal symptoms (EPS) is seen in quetiapine XR recipients. The most common potentially EPS-associated adverse events seen with quetiapine treatment were akathisia, restlessness and tremor. Rates of worsening of Simpson-Angus Scale and Barnes Akathisia Rating Scale scores were not dissimilar among quetiapine XR, quetiapine immediate release and placebo.