Starting Dose of Seroquel (Quetiapine)
For adults with schizophrenia, start quetiapine at 25 mg twice daily on Day 1, then rapidly titrate to 300-400 mg/day by Day 4 using divided doses. 1
Standard Adult Dosing for Schizophrenia
The FDA-approved titration schedule is: 1
- Day 1: 25 mg twice daily (total 50 mg/day)
- Day 2: Increase by 25-50 mg increments to 100 mg/day (divided doses)
- Day 3: 200 mg/day (divided doses)
- Day 4: 300-400 mg/day (divided doses)
The target therapeutic dose range is 300-450 mg/day, with a maximum of 750 mg/day. 1, 2
Indication-Specific Starting Doses
Bipolar Mania (Adults)
- Day 1: 100 mg/day in divided doses
- Day 2: 200 mg/day
- Day 3: 300 mg/day
- Day 4: 400 mg/day
- Target range: 400-800 mg/day 1
Bipolar Depression (Adults)
- Day 1: 50 mg once daily at bedtime
- Day 2: 100 mg
- Day 3: 200 mg
- Day 4: 300 mg (target dose) 1
Special Populations Requiring Lower Starting Doses
Elderly Patients
Start at 50 mg/day with slower titration in 50 mg/day increments. 1 The American Academy of Family Physicians recommends an even more conservative approach of 12.5 mg twice daily initially. 3
Hepatic Impairment
Start at 25 mg/day with daily increases of 25-50 mg until reaching an effective dose. 1 This population requires particularly cautious dose escalation. 4
Patients on CYP3A4 Inhibitors
Reduce the quetiapine dose to one-sixth of the original dose when co-administered with potent CYP3A4 inhibitors (ketoconazole, itraconazole, ritonavir). 1
Dosing Frequency
Twice-daily dosing is as effective as three-times-daily administration for the same total daily dose. 5 The 450 mg/day dose given as 225 mg twice daily showed equivalent efficacy to 150 mg three times daily. 5
Clinical Considerations
Monitor for orthostatic hypotension during initial titration, as this is a common dose-related adverse effect. 3 Somnolence is the most frequently reported adverse event, particularly during dose escalation. 2
Maximum therapeutic effects occur at doses ≥250 mg/day, with clinical efficacy being dose-related across the 150-750 mg/day range. 4 Patients who do not fully respond to lower doses should have their dose increased to 400 mg/day or above. 6
The drug can be administered with or without food, providing flexibility in dosing schedules. 1
Key Advantages of This Titration Schedule
The rapid titration to therapeutic doses by Day 4 allows for: 1
- Quick achievement of antipsychotic efficacy
- Minimal delay in symptom control
- Reduced risk of prolonged subtherapeutic dosing
Unlike clozapine, quetiapine requires no baseline blood monitoring or weekly blood counts, making initiation straightforward in outpatient settings. 2