Dosing and switching strategies for quetiapine fumarate.

BACKGROUND: The atypical antipsychotic agent quetiapine fumarate has demonstrated efficacy and tolerability in clinical trials in patients with chronic or subchronic exacerbations of schizophrenic symptoms.
OBJECTIVE: This review summarizes clinical trial data and other practical information regarding the initiation and routine administration of quetiapine. Appropriate strategies for switching from other antipsychotic agents to quetiapine are also discussed.
RESULTS: Quetiapine is an appropriate initial treatment for psychotic disturbances in patients with schizophrenia of any stage and for those in whom a therapeutic switch is indicated for clinical reasons, such as inability to tolerate the side effects of treatment. Titration to 400 mg/d is recommended using the following schedule, administered BID in divided doses: day 1, 50 mg; day 2, 100 mg: day 3, 200 mg; day 4, 300 mg; and day 5, 400 mg. In patients who respond to quetiapine, therapy should be continued at the optimal dose that maintains remission, within the range of 150 to 750 mg/d. When a change in therapy is indicated, several strategies for switching from one antipsychotic agent to another may be applied to switching to quetiapine. Whereas studies have shown that an abrupt switch to or withdrawal from quetiapine does not produce significant clinical consequences, in practice the switch should be carefully individualized to minimize the potential for psychotic relapse or development of withdrawal symptoms.
CONCLUSIONS: Quetiapine has antipsychotic effects and good tolerability at doses from 150 to 750 mg/d. Patients can be switched to quetiapine and their treatment individualized to achieve the optimal therapeutic effect with a minimum of dose-limiting side effects. There are several strategies for switching to quetiapine from another antipsychotic agent that do not appear to cause significant exacerbation of psychosis or withdrawal reactions.