Quetiapine (Seroquel) Dosing for Schizophrenia and Bipolar Disorder
For adult schizophrenia, start quetiapine at 25 mg twice daily on Day 1, escalate to 300-400 mg/day by Day 4, with a therapeutic range of 150-750 mg/day and maximum dose of 750 mg/day. 1
Schizophrenia Dosing in Adults
Initial Titration Schedule
- Day 1: 25 mg twice daily 1
- Day 2: Increase to 50-100 mg total daily (divided doses) 1
- Day 3: Increase to 150-200 mg total daily (divided doses) 1
- Day 4: Target 300-400 mg/day 1
- Further adjustments can be made in 25-50 mg twice daily increments, with intervals of at least 2 days 1
Therapeutic Dosing
- Recommended dose range: 150-750 mg/day 1
- Maximum dose: 750 mg/day 1
- Fixed-dose studies demonstrate that 150-450 mg/day is effective and no less efficacious than higher doses of 600-750 mg/day 2
- The optimum dose is likely greater than 250 mg/day based on placebo-controlled trials 3
Rapid Escalation Option
- For acutely ill hospitalized patients, escalation to 400 mg/day can be safely accomplished in 2-3 days rather than the standard 5 days, with similar tolerability 4
Schizophrenia Dosing in Adolescents (13-17 years)
- Day 1: 25 mg twice daily 1
- Day 2: 100 mg total daily (divided doses) 1
- Day 3: 200 mg total daily (divided doses) 1
- Day 4: 300 mg total daily (divided doses) 1
- Day 5: 400 mg total daily (divided doses) 1
- Therapeutic range: 400-800 mg/day 1
- Maximum dose: 800 mg/day 1
- Further adjustments should be in increments no greater than 100 mg/day 1
Bipolar Mania Dosing in Adults
Acute Treatment (Monotherapy or Adjunct to Lithium/Divalproex)
- Day 1: 100 mg total daily (divided doses) 1
- Day 2: 200 mg total daily (divided doses) 1
- Day 3: 300 mg total daily (divided doses) 1
- Day 4: 400 mg total daily (divided doses) 1
- Further adjustments up to 800 mg/day by Day 6 in increments no greater than 200 mg/day 1
- Therapeutic range: 400-800 mg/day 1
- Maximum dose: 800 mg/day 1
Maintenance Therapy
- Continue 400-800 mg/day as adjunct to lithium or divalproex 1
- Patients generally continue on the same dose on which they were stabilized 1
Bipolar Mania Dosing in Children/Adolescents (10-17 years)
- Day 1: 25 mg twice daily 1
- Day 2: 100 mg total daily (divided doses) 1
- Day 3: 200 mg total daily (divided doses) 1
- Day 4: 300 mg total daily (divided doses) 1
- Day 5: 400 mg total daily (divided doses) 1
- Therapeutic range: 400-600 mg/day 1, 5
- Maximum dose: 600 mg/day 1
Bipolar Depression Dosing in Adults
- Administer once daily at bedtime 1
- Day 1: 50 mg 1
- Day 2: 100 mg 1
- Day 3: 200 mg 1
- Day 4: 300 mg 1
- Recommended and maximum dose: 300 mg/day 1
- Both 300 mg/day and 600 mg/day showed efficacy, with no significant differences in treatment outcomes between these doses 6
Special Population Adjustments
Elderly Patients
- Start at 50 mg/day 1
- Increase in 50 mg/day increments based on clinical response and tolerability 1
- Use slower titration due to increased risk of orthostatic hypotension and sedation 5
- Monitor blood pressure during dose escalation, particularly in the first 3-5 days 5
Hepatic Impairment
Drug Interactions
- With CYP3A4 inhibitors (ketoconazole, itraconazole, ritonavir): Reduce dose to one-sixth of original dose 1
- With CYP3A4 inducers (phenytoin, carbamazepine, rifampin): Increase dose up to 5-fold when used chronically (>7-14 days) 1
Critical Monitoring Considerations
- Monitor for orthostatic hypotension, especially during initial dose titration 7, 5
- Orthostatic hypotension is most problematic in the first 3-5 days of treatment 5
- Quetiapine can be taken with or without food 1
- Common adverse events include dry mouth, sedation, somnolence, dizziness, and constipation 6
- Weight gain of approximately 2.1 kg occurs in short-term trials 8
- Quetiapine has minimal extrapyramidal symptoms and does not elevate prolactin levels 8, 3