What is the recommended dosage of Buspar (buspirone) for treating generalized anxiety disorder (GAD)?

Buspirone (BuSpar) Dosing for Generalized Anxiety Disorder

For treating generalized anxiety disorder (GAD) in adults, start buspirone at 15 mg daily (either 7.5 mg twice daily or 5 mg three times daily), then titrate to a target dose of 30 mg daily (15 mg twice daily or 10 mg three times daily), with a maximum dose of 60 mg daily if needed. 1

Initial Dosing Strategy

• Start with 15 mg/day divided doses: Begin with either 7.5 mg twice daily or 5 mg three times daily 1, 2
• The lower starting dose minimizes initial side effects while establishing tolerability 3

Titration Schedule

• Increase gradually over 2-4 days: Titrate from the initial 15 mg/day to the target dose of 30 mg/day 1
• The standard therapeutic dose is 30 mg daily, administered as either:
  • 15 mg twice daily (BID), OR
  • 10 mg three times daily (TID) 2, 4
• Both BID and TID regimens show equivalent efficacy and safety, though BID dosing may improve compliance 2, 4

Maximum Dosing

• Maximum dose: 60 mg/day (20 mg three times daily or 30 mg twice daily) 5, 1
• Most patients respond adequately to 15-30 mg/day without requiring maximum doses 6

Critical Timing Considerations

• Onset of effect: 2-4 weeks - Patients must understand that buspirone does not provide immediate anxiety relief like benzodiazepines 5, 7
• This delayed onset makes buspirone inappropriate for patients requiring rapid symptom control 7
• A full therapeutic trial requires maintaining the target dose for at least 2-4 weeks before assessing efficacy 5

Special Populations

Elderly Patients

• Use the same starting dose (5 mg twice daily) as in younger adults 5
• Maximum dose remains 20 mg three times daily (60 mg/day) 5
• Pharmacokinetics are similar in elderly patients, though individual sensitivity may vary 1

Hepatic or Renal Impairment

• Avoid buspirone in severe hepatic or renal impairment - the drug shows increased plasma levels and prolonged half-life in these patients 1
• If mild-to-moderate impairment, use lower doses with careful monitoring 1

Important Clinical Caveats

Drug Interactions

• CYP3A4 inhibitors (e.g., ketoconazole, erythromycin, grapefruit juice): Significantly increase buspirone levels; reduce buspirone dose and monitor closely 1
• CYP3A4 inducers (e.g., rifampin): May require higher buspirone doses to maintain efficacy 1
• MAO inhibitors: Contraindicated due to risk of elevated blood pressure 1

Laboratory Interference

• Discontinue buspirone 48 hours before urine catecholamine testing - it interferes with metanephrine/catecholamine assays and can cause false-positive results for pheochromocytoma 1

Patient Selection

• Buspirone is most appropriate for patients with chronic GAD who can tolerate gradual symptom improvement 7
• Not recommended for panic disorder - studies have been inconclusive 7
• Ideal for patients where benzodiazepine dependence is a concern 7, 3

Long-Term Use

• Buspirone can be safely used for up to 12 months when clinically indicated 6
• No withdrawal syndrome occurs with abrupt discontinuation, even after prolonged use 6
• Periodically reassess the need for continued therapy when used beyond several months 6

Common Adverse Effects

• Most frequent: dizziness, headache, nausea, nervousness, and lightheadedness 3, 4
• Palpitations occur more frequently with BID dosing (5%) versus TID dosing (1%) 4
• Overall adverse event incidence is low and similar between dosing regimens 2, 4
• No sedation, psychomotor impairment, abuse potential, or dependence reported 3