What is the dosing for Seroquel (Quetiapine)?

Quetiapine (Seroquel) Dosing Guidelines

The initial dosing for Quetiapine (Seroquel) should start at 12.5 mg twice daily, with a maximum recommended dose of 200 mg twice daily for most conditions. 1

Initial Dosing and Titration Schedule

Quetiapine requires careful titration to minimize side effects while achieving therapeutic efficacy:

• Day 1: Start with 12.5 mg twice daily (25 mg total daily dose)
• Days 2-3: Increase to 25 mg twice daily (50 mg total daily dose)
• Days 4-5: Increase to 50 mg twice daily (100 mg total daily dose)
• Days 6-7: Increase to 100 mg twice daily (200 mg total daily dose)
• Further titration: May increase up to 200 mg twice daily (400 mg total daily dose) based on response and tolerability

This titration schedule is particularly important to minimize the risk of orthostatic hypotension, which can occur early in treatment 1.

Dosing Considerations by Patient Population

Elderly Patients

• Start at lower doses (12.5 mg once or twice daily)
• Titrate more slowly (e.g., increase by 25 mg every 3-7 days)
• Target lower maximum doses (typically 50-100 mg twice daily)
• Monitor closely for sedation and orthostatic hypotension 1

Hepatic Impairment

• Start with 25 mg/day
• Increase in increments of 25-50 mg/day as tolerated
• Plasma levels may be 30-50% higher than in patients with normal hepatic function 2

Administration Timing

Quetiapine can be administered in either twice-daily (BID) or three-times-daily (TID) regimens:

• Twice-daily dosing (BID) is equally effective as three-times-daily dosing and improves adherence 3
• Evening dosing may be preferred when sedation is a concern or when insomnia is a target symptom

Monitoring During Treatment

During quetiapine treatment, monitor for:

1. Orthostatic hypotension, particularly during initial titration
2. Sedation and somnolence (most common side effect)
3. Metabolic changes (weight gain, hyperglycemia)
4. QTc interval prolongation (though less common than with some other antipsychotics)
5. Extrapyramidal symptoms (notably, quetiapine has a placebo-level incidence of EPS) 4

Drug Interactions

Important drug interactions to consider:

• CYP3A4 inhibitors (e.g., ketoconazole, itraconazole): Reduce quetiapine dose to one-sixth of original dose 2
• CYP3A4 inducers (e.g., phenytoin, carbamazepine): May require up to 5-fold increase in quetiapine dose 2
• When discontinuing CYP3A4 inducers, reduce quetiapine dose to original level within 7-14 days 2

Common Pitfalls and Caveats

1. Underdosing: Starting at too low a dose and failing to titrate to an effective dose (minimum effective dose is typically 300-400 mg/day for schizophrenia) 5

2. Too-rapid titration: Increasing the dose too quickly can lead to intolerable side effects and discontinuation

3. Failure to monitor for metabolic effects: Regular monitoring for weight gain and metabolic changes is essential

4. Abrupt discontinuation: When discontinuing, taper gradually to minimize withdrawal symptoms

5. Overlooking drug interactions: Particularly with CYP3A4 inhibitors or inducers, which significantly affect quetiapine levels 2

Quetiapine's favorable side effect profile, particularly its low risk of extrapyramidal symptoms and prolactin elevation, makes it a valuable option for patients who cannot tolerate other antipsychotics 4, 6.