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What is Seroquel?

Seroquel (quetiapine fumarate), an oral medication for the management of the manifestations of psychotic disorders (including schizophrenia), was cleared by the FDA for marketing on September 29, 1997. Seroquel is a new "atypical" antipsychotic agent in a new chemical class called dibenzothiazepine derivatives. Seroquel is manufactured by Zeneca Pharmaceuticals.

What does Seroquel treat?

Findings from extensive clinical trials have shown Seroquel to be effective in the treatment of both positive (e.g., delusions, thought disorder, and hallucinations) and negative (e.g., social withdrawal, lack of energy, apathy, and reduced ability to express emotion) symptoms of schizophrenia.

Seroquel affects a broad range of neurotransmitter receptors, including serotonin receptors. In comparative clinical trials, Seroquel has been shown to be as effective as standard antipsychotic agents, such as chlorpromazine (Thorazine) and haloperidol (Haldol).

What are the advantages of Seroquel over other antipsychotics?

The reported clinical studies show that Seroquel has "full antipsychotic activity" and the advantage of fewer or less severe motor side effects. In test groups unwanted reactions were usually rated mild to moderate, and the active-treatment groups did not differ from the placebo group in scores measuring akathisia (complaints of restlessness accompanied by fidgety movements) or involuntary movements. Tremor did not develop in any patient receiving active treatment.

What is the standard dose of Seroquel?

Seroquel will be available by prescription throughout the U.S. beginning in autumn 1997 in strengths of 25 mg (peach), 100 mg (yellow), and 200 mg (white) tablets. In clinical trials, it was effective in a dose range of 150 mg/day to 750 mg/day. A maximum therapeutic effect was seen at 300 mg/day in a dosing trial. In other studies, doses in the range of 400-500 mg/day were effective. Taking Seroquel two to three times a day is recommended.

What are the most common side effects of Seroquel?

Reported side effects are similar to those seen with other antipsychotics. These include sleepiness; hypotension (abnormally low blood pressure); digestive problems (constipation, dry mouth, indigestion); and dizziness. Such effects are usually seen when the medication is first taken. They are mild and generally improve without specific treatment. Seroquel should be used with particular caution in patients with known cardiovascular disease, cerebrovascular disease, or conditions associated with hypotension.

How long should I stay on Seroquel?

The effectiveness of Seroquel for long-term use and its interaction with other medications have not been studied extensively. Therefore, patients taking this drug for extended periods of time should be monitored closely by a physician and re-evaluated over time.

Reviewed by Samuel J. Keith, M.D., professor and chairman, Department of Psychiatry, The University of New Mexico Health Sciences Center, School of Medicine (Sept. 1997)