Starting Dose for Extended-Release Seroquel (Quetiapine)
The recommended initial dose for extended-release quetiapine (Seroquel XR) is 50 mg once daily at bedtime, with gradual titration based on response and tolerability.
Dosing Guidelines by Indication
Schizophrenia
- Initial dose: 50 mg once daily at bedtime
- Day 2: 100 mg once daily
- Day 3: 200 mg once daily
- Day 4: 300 mg once daily
- Target dose range: 400-800 mg once daily 1
Bipolar Depression
- Initial dose: 50 mg once daily at bedtime
- Day 2: 100 mg once daily
- Day 3: 200 mg once daily
- Day 4: 300 mg once daily
- Target dose: 300 mg once daily 1
Bipolar Mania
- Initial dose: 50 mg once daily at bedtime
- Day 2: 100 mg once daily
- Day 3: 200 mg once daily
- Day 4: 300 mg once daily
- Day 5: 400 mg once daily
- Target dose range: 400-800 mg once daily 1
Administration Considerations
- Take with or without food - A light meal has no significant effect on absorption, though high-fat meals can increase drug exposure 2
- Evening dosing is preferred - This helps mitigate daytime sedation 2
- Once-daily administration - XR formulation allows for once-daily dosing versus twice-daily with immediate-release 1, 2
Special Populations
Elderly Patients
- Start at a lower dose of 50 mg/day
- Increase in increments of 50 mg/day based on response and tolerability 1
- Use caution due to increased risk of orthostatic hypotension
Hepatically Impaired Patients
- Start at 25 mg/day
- Increase daily in increments of 25-50 mg/day based on clinical response and tolerability 1
Pharmacokinetic Considerations
The extended-release formulation provides:
- Similar overall drug exposure (AUC) compared to immediate-release
- Lower peak concentration (Cmax) than immediate-release
- Less pronounced D2 receptor occupancy peak
- More sustained receptor occupancy over 24 hours 3, 2
Advantages of Extended-Release vs. Immediate-Release
- Reduced sedation intensity during initial hours after administration 4
- Less variable drug exposure (39.2% vs 51.2% coefficient of variation) 2
- Simplified dosing schedule (once daily vs twice daily)
- Potentially better adherence due to once-daily dosing
Important Monitoring Considerations
- Monitor for orthostatic hypotension, especially during initial dose titration
- Watch for excessive sedation, particularly in elderly patients
- Be aware of potential metabolic effects with long-term use
- Consider regular monitoring of weight, blood glucose, and lipid profiles
Common Pitfalls to Avoid
- Starting at too high a dose - This increases risk of sedation and orthostatic hypotension
- Titrating too quickly - Follow the recommended gradual titration schedule
- Morning dosing - Evening dosing helps minimize daytime sedation
- Failure to adjust dose in elderly or hepatically impaired patients - These populations require lower starting doses and more cautious titration
- Abrupt discontinuation - When stopping treatment, gradual tapering is recommended
Remember that the extended-release formulation was specifically designed to provide more consistent plasma levels throughout the day, which may improve tolerability while maintaining efficacy.