Quetiapine is a medication used to treat schizophrenia and bipolar disorder. It works by regulating the levels of serotonin and dopamine in the brain, which are neurotransmitters that control communication between neurons and influence emotions, mood, memory, and sleep.
Quetiapine is a prescription medication available in pharmacies as tablets, sold under the brand name Seroquel or as the generic quetiapine fumarate.
Quetiapine is an antipsychotic that should only be used under medical supervision, as it may cause side effects such as difficulty speaking or moving, dizziness, dry mouth, or mood changes.
Indications for use
Quetiapine is prescribed for the following conditions:
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Schizophrenia;
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Moderate to severe manic episodes in bipolar disorder;
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Depressive episodes associated with bipolar disorder;
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Prevention of recurrence of manic or depressive episodes in people with bipolar disorder who were previously treated with quetiapine.
In addition, quetiapine may be prescribed as an add-on treatment for major depressive disorder in people who have not responded to other antidepressants.
Dosing instructions
Quetiapine is available as tablets containing between 25 mg and 300 mg, and it is indicated for adults aged 18 years and older.
The dosage of quetiapine varies depending on the condition being treated:
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Schizophrenia: The typical starting dose is 50 mg on the first day of treatment, 100 mg on the second day, 200 mg on the third day, and 300 mg on the fourth day. The total daily dose should be divided into two doses. After the fourth day, the doctor may adjust the dose to between 300 and 450 mg per day, depending on response and tolerance. Some people may need doses ranging from 150 to 750 mg daily.
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Moderate to severe manic episodes in bipolar disorder: The typical starting dose is 100 mg on the first day, increasing up to 400 mg by the fourth day. The dose may then be adjusted by a doctor to reach the effective dose, up to a maximum of 800 mg per day. The total daily dose should be divided into two doses.
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Depressive episodes in bipolar disorder: Taken once daily at bedtime. The dose increases gradually during the first few days, starting at 50 mg and reaching 300 mg by the fourth day. The recommended daily dose is 300 mg.
Quetiapine should be taken by mouth, with or without food, at the same time each day as directed by the doctor.
If a dose is missed, it should be taken as soon as remembered, unless it is almost time for the next one. In that case, skip the missed dose and take the next dose as scheduled. Do not double up to make up for a missed dose.
Side effects
The most common side effects of quetiapine include:
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Vomiting;
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Difficulty speaking or moving;
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Dizziness;
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Drowsiness;
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Fatigue;
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Heart palpitations;
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Stomach pain;
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Nasal congestion;
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Weight gain.
You should notify your doctor if you experience mood or behavioral changes, anxiety, panic attacks, trouble sleeping, impulsivity, irritability, agitation, aggression, depression, or suicidal thoughts.
Contraindications for use
Quetiapine should not be used by people who are allergic to any of its components. Before starting treatment, it is important to tell your doctor about any medications or supplements you are taking.
Medications that inhibit the cytochrome P450 3A4 enzyme, such as HIV protease inhibitors, azole antifungals, erythromycin, clarithromycin, and nefazodone, can affect the absorption of quetiapine, so its dosage may need to be adjusted.
This medication should be used with caution and under medical supervision by people with liver or heart problems, cataracts, glaucoma, or urinary retention. It is should also be avoided during pregnancy or breastfeeding, unless a doctor determines that the potential benefits outweigh the risks.
Additionally, quetiapine should not be used by children under 13 years of age for schizophrenia or by children under 10 years old for bipolar disorder.