What are the main uses of Quetiapine (Seroquel)?

Main Uses of Quetiapine (Seroquel)

Quetiapine is primarily used for the treatment of schizophrenia, bipolar disorder (both manic and depressive episodes), and as an adjunctive treatment for major depressive disorder.

FDA-Approved Indications

• Schizophrenia: Quetiapine is effective in reducing both positive and negative symptoms of schizophrenia 1
• Bipolar Disorder:
  • Acute manic episodes 2
  • Bipolar depression 3
  • Maintenance therapy for prevention of recurrence in bipolar disorder 3

Off-Label Uses

• Major Depressive Disorder: Used as an adjunctive treatment when standard antidepressants are insufficient 4
• Anxiety Disorders: Particularly effective for generalized anxiety disorder 4
• Insomnia: Used as a sedating agent, though not FDA-approved for this indication 2
• Delirium: Used in hospitalized and cancer patients for management of delirium symptoms 2

Mechanism of Action

• Quetiapine has antagonistic effects on multiple neurotransmitter receptors:
  • Serotonin receptors (5-HT1A and 5-HT2A)
  • Dopamine receptors (D1 and D2)
  • Histamine receptors (H1)
  • Adrenergic receptors (alpha1 and alpha2) 5
• This broad receptor profile contributes to its efficacy for various psychiatric conditions 1

Dosing Considerations

• Schizophrenia: Typical dosage range 150-800 mg/day 6
• Bipolar Disorder:
  • For acute mania: Approved for adults 2
  • For bipolar depression: Effective as monotherapy 3
• Delirium: Starting dose of 25 mg immediate release, can be given twice daily if scheduled dosing required 2
• Pediatric Use: Has been used in children and adolescents with bipolar disorder and schizophrenia, though with limited FDA approval for these populations 2

Important Considerations

• Available in both immediate-release (IR) and extended-release (XR) formulations 3
• Common side effects include:
  • Sedation
  • Dry mouth
  • Somnolence
  • Dizziness
  • Orthostatic hypotension 2
• Less likely to cause extrapyramidal symptoms (EPS) than typical antipsychotics 2
• Metabolic side effects (weight gain, diabetes risk) are moderate compared to other atypical antipsychotics 1
• Requires dose reduction in elderly patients and those with hepatic impairment 2

Clinical Pearls

• Quetiapine's sedating properties make it useful for patients with agitation or insomnia, but may be problematic for those requiring alertness 2
• There have been reports of quetiapine abuse and misuse, particularly in prison populations and patients with substance use disorders 5
• When switching from immediate-release to extended-release formulation, the same daily dose can generally be maintained 3