What is the normal dosage of Seroquel (quetiapine)?

Normal Seroquel (Quetiapine) Dosage

For schizophrenia in adults, the standard therapeutic dosage range is 150-750 mg/day, with most patients responding to 400-600 mg/day administered in divided doses. 1

Standard Dosing by Indication

Schizophrenia - Adults

• Initial titration schedule: 1
  • Day 1: 25 mg twice daily
  • Day 2: Increase to 50-75 mg twice daily
  • Day 3: Increase to 100 mg twice daily
  • Day 4: Target 300-400 mg/day in divided doses
• Therapeutic range: 150-750 mg/day 1, 2
• Maximum dose: 750 mg/day 1
• Optimal dosing: Most patients achieve therapeutic response at 400 mg/day or above, though 150-450 mg/day has demonstrated efficacy in fixed-dose studies 2, 3

Schizophrenia - Adolescents (13-17 years)

• Initial titration: 1
  • Day 1: 25 mg twice daily
  • Day 2: 100 mg/day total (divided doses)
  • Day 3: 200 mg/day total
  • Day 4: 300 mg/day total
  • Day 5: 400 mg/day total
• Therapeutic range: 400-800 mg/day 1
• Maximum dose: 800 mg/day 1

Bipolar Mania - Adults

• Initial titration: 1
  • Day 1: 100 mg/day total (divided doses)
  • Day 2: 200 mg/day total
  • Day 3: 300 mg/day total
  • Day 4: 400 mg/day total
• Therapeutic range: 400-800 mg/day 1
• Maximum dose: 800 mg/day 1

Bipolar Depression - Adults

• Administered once daily at bedtime: 1
  • Day 1: 50 mg
  • Day 2: 100 mg
  • Day 3: 200 mg
  • Day 4: 300 mg
• Target dose: 300 mg/day 1

Special Population Dosing

Elderly Patients

• Initial dose: 12.5 mg twice daily for psychiatric conditions or delirium 4, 5
• Alternative starting dose: 50 mg/day with slower titration 1
• Dose escalation: Increase in 50 mg/day increments based on clinical response 1
• Maximum dose: 200 mg twice daily, though lower doses often sufficient 4
• Key consideration: More sedating with risk of transient orthostatic hypotension 4

Hepatic Impairment

• Initial dose: 25 mg/day 1
• Dose escalation: Increase daily in 25-50 mg/day increments to effective dose 1

Dosing Frequency

Quetiapine can be administered twice daily (BID) rather than three times daily (TID) without loss of efficacy. 6

• Studies demonstrate 225 mg BID is equivalent to 150 mg TID at the same total daily dose 6
• BID dosing improves medication adherence while maintaining therapeutic effect 6

Rapid Dose Escalation

In acutely ill hospitalized patients, quetiapine can be escalated to 400 mg/day in 2-3 days rather than the standard 5 days with similar safety and tolerability. 7

• Faster escalation schedules (2-day or 3-day) show comparable adverse event profiles to standard 5-day titration 7
• This approach is appropriate when rapid therapeutic response is clinically necessary 7

Drug Interactions Requiring Dose Adjustment

With CYP3A4 Inhibitors

• Reduce quetiapine dose to one-sixth of original dose when co-administered with potent CYP3A4 inhibitors (ketoconazole, itraconazole, ritonavir) 1
• When inhibitor discontinued, increase quetiapine dose by 6-fold 1

With CYP3A4 Inducers

• Increase quetiapine dose up to 5-fold when used with chronic CYP3A4 inducers (phenytoin, carbamazepine, rifampin) for >7-14 days 1
• When inducer discontinued, reduce to original dose within 7-14 days 1

Clinical Pearls

• No routine ECG or blood monitoring required 2
• Placebo-level incidence of extrapyramidal symptoms (EPS) at all doses 2, 6
• No sustained prolactin elevation 6
• Can be taken with or without food 1
• Doses of 400 mg or above should be used in patients who do not fully respond to lower doses 2
• Wide clinical dosing range (150-750 mg/day) allows for individualized titration 2