Short-term benefits of higher-dose quetiapine (up to 1600 mg/day) are maintained long term

Introduction: Quetiapine (‘Seroquel’) is an established treatment for schizophrenia currently approved at doses up to 750 mg/day (800 mg/day in the USA); however, some patients may benefit from treatment with higher doses. Methods: This open-label study of 35 hospitalised patients with schizophrenia, schizoaffective disorder, bipolar disorder or alcoholinduced psychosis investigated the efficacy and tolerability of quetiapine at doses up to 1600 mg/day during a 4-week acute phase and at doses up to 1000 mg/day during a 14-month followup after discharge. All patients had stopped their previous antipsychotic medication due to extrapyramidal symptoms (EPS). The Clinical Global Impression of Improvement (CGI-I) scale was the primary efficacy evaluation. Results: Eleven patients (31.4%) received 1000-1600 mg/day quetiapine during the acute phase, 15 (42.9%) received 600-800 mg/day and 9 (25.7%) received ≤400 mg/day. Of the 11 patients on ≥1000 mg/day, 5 (14.3%) continued on 800-1000 mg/day after discharge. Quetiapine was well tolerated with a low incidence of side effects and no EPS were observed with dose elevation. After 4 weeks’ hospitalisation, CGI-I scale results showed that quetiapine improved symptomatology in 33 (94.3%) patients: 13 (37.1%) ‘very much improved’; 13 (37.1%) ‘much improved’ and 7 (20.0%) ‘minimally improved’. No change was observed in 2 (5.7%) patients, and no patient experienced symptom deterioration. Conclusions: This study demonstrates that short-term treatment with quetiapine at doses up to 1600 mg/day is well tolerated and effective in patients with psychoses and that these benefits can be maintained for up to 14 months with doses up to 1000 mg/day.