SEROQUEL (Quetiapine) is approved to treat psychotic disorders such as schizophrenia. It belongs to a class of drugs called atypical or second-generation antipsychotics. While all antipsychotics usually improve symptoms such as agitation, delusions, hallucinations, and suspiciousness, atypical antipsychotics claim to improve “negative” symptoms such as apathy, disorientation, emotional withdrawal, and lack of pleasure more than older antipsychotics. However, there is no clear evidence that atypical antipsychotics are more effective or are better tolerated than the older conventional antipsychotics such as haloperidol (HALDOL).
The Food and Drug Administration (FDA) issued a public health advisory on April 11, 2005, to warn that the drugs known as the atypical antipsychotics are associated with an increased risk of death when used to treat dementia in elderly patients.
The atypical antipsychotics affected by the FDA advisory are aripiprazole (ABILIFY), olanzapine (ZYPREXA), quetiapine (SEROQUEL), risperidone (RISPERDAL), clozapine (CLOZARIL), and ziprasidone (GEODON). None of these drugs, however, are approved for the treatment of behavioral disorders in patients with dementia.
In September 2003, the FDA ordered that the professional product labeling for these drugs warn that patients should be monitored for the symptoms of diabetes mellitus. The drugs requiring the new warning are aripiprazole (ABILIFY), clozapine (CLOZARIL), olanzapine (ZYPREXA), quetiapine (SEROQUEL), risperidone (RISPERDAL), and ziprasidone (GEODON).
Seroquel can have serious adverse effects. These include neuroleptic malignant syndrome (NMS), a condition that includes a dangerously high fever, muscle rigidity, and altered mental states, heatstroke that can be fatal, and tardive dyskinesia, a serious adverse effect that may be reversible in its early stages. Early signs of tardive dyskinesia include unusual movements of the tongue or mouth, or tremor. If progressive, it may lead to uncontrollable movements of the arms, legs, and tongue, for which there is no known effective treatment. Women and older people are more prone to tardive dyskinesia. Extrapyramidal effects, such as drug-induced parkinsonism, may cause a shuffle when walking.
Seroquel can cause dizziness and low blood pressure. Common anticholinergic effects are drowsiness and dry mouth (see the Adverse Effects of Antipsychotic Drugs table in Antipsychotic Drugs: Another Group of Dangerously Overused Drugs). More than 20 percent of people taking quetiapine gained weight, sometimes accompanied by an increase in cholesterol level. A common adverse effect is drowsiness. Generally, older people develop adverse effects more often.
In one species of animal (beagles) but not in any other animals, quetiapine caused cataracts. Until the effect of quetiapine on the eyes of humans is determined, you should have eye exams at initiation of treatment and every six months, such as slit lamp exams, to detect the formation of cataracts.