Quetiapine (Generic): Uses and Typical Dosages
Quetiapine is an atypical antipsychotic medication primarily used to treat schizophrenia, bipolar disorder (both mania and depression), and as an adjunctive therapy for major depressive disorder, with dosing regimens that vary by indication and patient characteristics.
Primary Indications and Dosing
Schizophrenia
- Adults: 300-400 mg/day in 2-3 divided doses; therapeutic range 150-750 mg/day 1, 2
- Adolescents (13-17 years): Starting at lower doses with target of 400-800 mg/day 3
- Elderly: Lower starting dose (25 mg/day), with slower titration due to 30-50% reduced clearance 3
Bipolar Disorder
- Bipolar Mania:
- Adults: 400-800 mg/day in divided doses
- Children/Adolescents (10-17 years): Demonstrated efficacy in 3-week trials 3
- Bipolar Depression: Effective without increasing risk of triggering manic episodes 1
Off-Label Uses
- Major Depressive Disorder: As augmentation therapy 4
- Anxiety Disorders: Strong evidence for generalized anxiety disorder 4
- Insomnia: Low-dose (25-100 mg) at bedtime 5
- Dementia-related behavioral disturbances: Low doses (12.5-25 mg twice daily) in elderly patients, though carries FDA black box warning for increased mortality 6
Administration Considerations
Hepatic Impairment
- Starting dose: 25 mg/day
- Increase in increments of 25-50 mg/day based on response and tolerance 3
Geriatric Patients
- Start at 25 mg/day with slower titration
- Careful monitoring for orthostatic hypotension and excessive sedation 6, 3
- Consider ECG monitoring in high-risk patients 6
Side Effect Profile
Common Side Effects
- Sedation/somnolence
- Dizziness
- Orthostatic hypotension
- Weight gain (moderate compared to other atypicals) 2
Advantages Over Other Antipsychotics
- Placebo-level incidence of extrapyramidal symptoms across all doses 7, 2
- No significant elevation of prolactin levels 2
- No routine blood monitoring required (unlike clozapine) 7
- Favorable cognitive profile compared to typical antipsychotics 1, 2
Safety Considerations
- FDA black box warning for increased mortality in elderly patients with dementia-related psychosis 6
- QTc interval prolongation (though generally small and clinically insignificant) 1
- Metabolic effects (weight gain, hyperglycemia) though less pronounced than some other atypicals 1
Clinical Pearls
- Quetiapine is metabolized by CYP3A4; dose adjustments may be needed with enzyme inducers (phenytoin, carbamazepine) or inhibitors 8
- Higher doses (≥400 mg/day) should be considered in patients with inadequate response to lower doses 7
- Particularly useful in patients susceptible to extrapyramidal symptoms or those with parkinsonian features 7
- For insomnia, lower doses (25-100 mg) are typically used off-label, though evidence is limited 5
- In bipolar disorder, quetiapine has the advantage of efficacy in both manic and depressive phases 1
Quetiapine's versatility across multiple psychiatric conditions, combined with its favorable side effect profile regarding extrapyramidal symptoms and prolactin levels, makes it a valuable option in the psychopharmacological armamentarium, though metabolic monitoring remains important.