Known brand names include Seroquel.
An atypical (second-generation) antipsychotic taken by mouth. It treats schizophrenia, manic episodes of bipolar I disorder, and depressive episodes of bipolar disorder, and is used with lithium or divalproex for bipolar maintenance.
Exactly how quetiapine works is not clear. It may help by blocking receptors in the brain for dopamine and serotonin, two chemical messengers. The liver turns it into an active breakdown product, norquetiapine, which acts on the same targets and blocks the serotonin receptor even more strongly. Both also block histamine receptors and some adrenaline receptors.
It is absorbed quickly, reaching its highest blood level in about 1.5 hours, and the liver clears half of it in about 6 hours. Blocking adrenaline receptors probably explains why blood pressure can drop on standing, with dizziness, a fast heartbeat, and sometimes fainting, mostly early on while the dose is being raised. The breakdown product also blocks acetylcholine receptors, which adds to side effects such as constipation, and in some people this has led to a blocked bowel. Because the liver does most of the clearing, people with liver problems may end up with higher levels.
Quetiapine is an antipsychotic for schizophrenia, a mental illness that changes how someone thinks, feels, and acts, and for bipolar disorder, which causes episodes of depression, mania, and other unusual moods. In bipolar I disorder, it treats manic episodes, either alone or added to lithium or divalproex. It also treats depressed episodes of bipolar disorder on its own. It can help control symptoms but does not cure the illness.
For schizophrenia, it is used in adults and in teens 13 to 17, and for mania in adults and in children and teens 10 to 17. In adults, it also treats bipolar depression, and it is added to lithium or divalproex as long-term treatment to help prevent new episodes. In children and teens, the label advises starting it only after a thorough diagnosis and as part of a wider plan that includes counseling, school, and social support. It is not approved for children under 10 or for older adults with psychosis linked to dementia.
Sleepiness, dizziness, dry mouth, constipation, and tiredness are the common complaints, along with dizziness or fainting on standing. It can cause weight gain and raise blood sugar and cholesterol, and in young people it can raise blood pressure. The label treats neuroleptic malignant syndrome as dangerous, with high fever, stiff muscles, and confusion. It also warns about permanent movement problems, low white blood cell counts, heart rhythm changes, falls, seizures, thyroid changes, cataracts, trouble swallowing, and a higher risk of stroke and death in older adults with dementia.
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A clinician may order these while someone is taking it.
This is the boxed warning, the warning the FDA label prints first.
Older adults with dementia-related psychosis treated with antipsychotics have a higher risk of death; quetiapine is not approved for them. Antidepressants raised suicidal thoughts and behavior in children, teens, and young adults; monitor all patients for worsening or suicidality. Not approved under age 10.
Sources: [1]