Seroquel (Quetiapine) Dosing
Start quetiapine at 12.5-25 mg twice daily and titrate to a target dose of 300-400 mg/day in divided doses, with a maximum of 750-800 mg/day for schizophrenia. 1, 2
Initial Dosing and Titration
The recommended starting dose is 12.5 mg twice daily for most indications, with a maximum of 200 mg twice daily per American Academy of Family Physicians guidelines. 1 However, for schizophrenia specifically, a more aggressive titration schedule is appropriate:
Standard Titration Schedule for Schizophrenia:
- Day 1: 25-50 mg twice daily 3, 4
- Day 2: 100 mg total daily (50 mg twice daily) 4
- Day 3: 200 mg total daily (100 mg twice daily) 4
- Day 4: 300 mg total daily (150 mg twice daily) 4
- Day 5 and beyond: 400 mg total daily (200 mg twice daily) 4
Target Therapeutic Dose:
- Optimal dosing range: 300-400 mg/day in 2-3 divided doses 2, 5
- Licensed maximum: 750-800 mg/day 5, 4
- Fixed-dose studies demonstrate that 150-450 mg/day is more effective than placebo, with no additional benefit at 600-750 mg/day 5
Dosing Frequency
Quetiapine can be administered twice daily (BID) or three times daily (TID) with equivalent efficacy. 6 A study comparing 225 mg BID versus 150 mg TID found no significant differences in efficacy measures, supporting twice-daily dosing despite the 7-hour elimination half-life 6. This allows for:
- Twice-daily dosing: More convenient for adherence 3, 6
- Three-times-daily dosing: May provide more stable coverage if needed 2, 6
Critical Safety Monitoring During Titration
Orthostatic Hypotension:
- Monitor blood pressure during initial dose titration, especially in elderly patients 3, 1, 7
- Exercise particular caution with concurrent CNS depressants due to additive psychomotor effects 7
Discontinuation:
- Never abruptly discontinue or rapidly decrease doses—withdrawal symptoms can occur 3, 7
- Taper gradually when stopping therapy
Special Considerations
Delirium Management:
- Start with 25 mg orally stat, then 25-50 mg twice daily scheduled dosing 3, 7
- For severe delirium, may use 50-100 mg twice daily 7
- Immediate-release formulation is preferred for acute settings to allow flexible titration 3
Administration:
- Administer on an empty stomach to maximize effectiveness 7
- No routine ECG or blood monitoring required 8
Common Pitfalls to Avoid
Do not exceed 750-800 mg/day based on the "high-dose theory"—robust controlled data show standard dosing (300-450 mg/day) is appropriate and equally effective. 5 Case reports suggesting benefit only at higher doses are not supported by controlled trials, and the belief that higher doses are required reflects misinterpretation of neuroimaging data showing low dopamine receptor occupancy (which is characteristic of quetiapine's mechanism, not a dosing inadequacy) 5.