From the Guidelines
Quetiapine is an atypical antipsychotic medication primarily used to treat schizophrenia, bipolar disorder, and as an adjunct therapy for major depressive disorder, with a suggested starting dose of 25 mg p.o. stat, as indicated in the management of delirium symptoms in adult patients 1. The typical starting dose is 25-50mg at bedtime, gradually increasing to an effective dose range of 150-800mg daily depending on the condition being treated.
- For schizophrenia, doses typically range from 300-800mg daily,
- while bipolar disorder may require 400-800mg daily.
- When used for depression, lower doses of 150-300mg are common. Quetiapine works by blocking multiple neurotransmitter receptors, particularly dopamine D2 and serotonin 5-HT2A receptors, which helps regulate mood, thinking, and behavior. Common side effects include sedation, dizziness, dry mouth, constipation, and weight gain. Metabolic monitoring is essential as quetiapine can cause increases in blood glucose, cholesterol, and triglycerides. The medication should be taken as prescribed, and patients should not stop taking it abruptly as this can lead to withdrawal symptoms. Quetiapine typically takes 2-4 weeks to show full therapeutic effects, though sedative effects may be noticed immediately, and is considered to be less likely to cause extrapyramidal symptoms (EPSEs) than other atypical antipsychotics 1. It is also used in the management of delirium symptoms in adult patients, with a suggested starting dose of 25 mg p.o. stat, and is considered to be sedating, with less likelihood of causing EPSEs compared to other atypical antipsychotics 1.
From the FDA Drug Label
Chronic antipsychotic treatment should generally be reserved for patients who appear to suffer from a chronic illness that (1) is known to respond to antipsychotic drugs, and (2) for whom alternative, equally effective, but potentially less harmful treatments are not available or appropriate
The use of Quetiapine is for the treatment of patients with chronic illnesses that are known to respond to antipsychotic drugs, such as schizophrenia and bipolar disorder, when alternative treatments are not available or appropriate 2.
- Key indications include:
- Schizophrenia
- Bipolar disorder
- Use should be reserved for patients with chronic illnesses that meet specific criteria, including response to antipsychotic drugs and lack of alternative treatments. Quetiapine should be prescribed in a manner that minimizes the occurrence of tardive dyskinesia 2.
From the Research
Use of Quetiapine (Atypical Antipsychotic)
Quetiapine is an atypical antipsychotic that is indicated for the treatment of:
- Schizophrenia 3, 4, 5, 6
- Bipolar disorder, including bipolar depression 3, 5, 6, 7
- Manic episodes 5, 6, 7
Mechanism of Action
The antipsychotic effects of quetiapine are thought to stem from interactions at serotonin 5-HT2 and dopamine D2 receptors 3. The antidepressant effects of quetiapine are poorly understood, but may be related to:
- Antagonism of 5-HT2A receptors in cortical regions
- Partial agonism of 5-HT1A in the prefrontal cortex
- Reduced synaptic reuptake of noradrenaline resulting from inhibition of the noradrenaline reuptake transporter by the quetiapine metabolite norquetiapine 3
Efficacy and Tolerability
Quetiapine has been shown to be effective in:
- Reducing positive and negative symptoms of schizophrenia 4, 5, 6
- Relieving acute depressive and manic symptoms in bipolar disorder 3, 5, 6, 7
- Preventing recurrence in patients with bipolar disorder who respond to quetiapine 3, 6 Quetiapine is generally well tolerated, with most treatment-emergent adverse events being of mild to moderate severity 3, 4, 6. Common adverse events include:
- Dry mouth
- Sedation
- Somnolence
- Dizziness
- Headache
Formulations
Quetiapine is available in both immediate release (IR) and extended release (XR) formulations, allowing for flexibility of dosing for individual patients 6. The XR formulation has similar bioavailability but prolonged plasma levels compared with the IR formulation, allowing for less frequent (once-daily) dosing 6.