Seroquel (Quetiapine) Dosing Pattern
Start quetiapine at 12.5 mg twice daily and titrate to a target dose of 300-450 mg/day administered in two divided doses, with a maximum of 200 mg twice daily (400 mg/day total) for most indications. 1
Initial Titration Schedule
For schizophrenia, use the following rapid titration schedule:
- Day 1: 50 mg/day
- Day 2: 100 mg/day
- Day 3: 200 mg/day
- Day 4: 300 mg/day
- Day 5: 400 mg/day (target dose) 2
This aggressive titration achieves therapeutic dosing within 5 days and is supported by clinical trial data demonstrating efficacy at 150-450 mg/day 3, 4.
Target Dosing Range
The optimal therapeutic dose is 300-450 mg/day given in two divided doses (BID). 2, 4
- Doses of 150-450 mg/day are more effective than placebo and equally effective as higher doses of 600-750 mg/day 5
- Twice-daily dosing (BID) is as effective as three-times-daily (TID) dosing despite quetiapine's 6-hour half-life 4
- The licensed maximum is 750-800 mg/day, though robust controlled data do not support routine use above 450 mg/day 5
Special Populations
For elderly patients or those with hepatic/renal impairment, start at 25 mg/day with increments of 25-50 mg daily to reach a lower effective dose. 3
- Elderly patients have 20-30% higher plasma concentrations and 50% lower clearance 3
- Hepatic cirrhosis or severe renal impairment reduces clearance by approximately 25% 3
Critical Monitoring During Titration
Monitor for orthostatic hypotension, especially during the first week of dose escalation. 1
- Quetiapine causes sedation and orthostatic hypotension due to alpha-1 adrenergic blockade 1
- Assess blood pressure in supine and standing positions during initial titration 1
Drug Interactions Requiring Dose Adjustment
Reduce quetiapine dose to one-sixth (approximately 17% of original) when co-administered with strong CYP3A4 inhibitors (ketoconazole, itraconazole, ritonavir, nefazodone). 6
Increase quetiapine dose up to 5-fold when co-administered with strong CYP3A4 inducers (phenytoin, carbamazepine, rifampin, St. John's wort). 6
- When the CYP3A4 inducer is discontinued, reduce quetiapine back to the original dose within 7-14 days 6
Common Pitfalls to Avoid
Never abruptly discontinue quetiapine—taper gradually to prevent rebound insomnia, agitation, and symptom relapse. 7
Avoid alcohol while taking quetiapine, as it potentiates cognitive and motor impairment. 6
Do not routinely exceed 750 mg/day based on the "high-dose theory"—controlled data show no additional benefit above 450 mg/day for most patients. 5
Maintenance Therapy
Continue quetiapine at the optimal dose that maintains remission, within the range of 150-750 mg/day. 2