Quetiapine is classified as an atypical antipsychotic. It is used to treat psychotic disorders such as schizophrenia.
Quetiapine is thought to modify the actions of several chemicals in the brain. It is chemically related to another atypical antipsychotic agent, clozapine, but differs both chemically and pharmacologically from the earlier phenothiazine antipsychotics.
It is available 25-mg, 100-mg, and 200-mg tablets.
Initially, a dosage of 25 mg should be taken twice a day. Each dose should be increased by 25-50 mg increments every three to four days until a target dose of 300-400 mg per day, administered in two or three divided doses, is achieved. It is not known whether doses higher than 800 mg per day are safe.
Caution should be used in patients with heart disease because the drug may cause blood pressure to fall too low resulting in dizziness, rapid heartbeat, or fainting.
Quetiapine may cause liver damage. As a result, patients should notify their health care provider if they experience flu-like symptoms, notice yellowing of their skin or eyes, or experience abdominal pain. Liver function should be assessed periodically. The drug should be used cautiously in people with a history of liver disease or alcoholic cirrhosis.
Quetiapine may alter the function of the thyroid gland. Those taking supplements for low thyroid function may require dosage adjustments in their thyroid medication.
Quetiapine may increase cholesterol levels and contribute to the formation of cataracts. Because of this possibility, cholesterol levels should be checked periodically and yearly eye exams should be performed.
Quetiapine should be used carefully in those with a history of seizure disorders because it may increase the tendency to have seizures.
Quetiapine may cause extreme drowsiness and should be used carefully by people who need to be mentally alert.