What is the recommended initial dosing regimen for starting a patient on Buspar (buspirone)?

Initial Dosing Regimen for Buspirone (Buspar)

The recommended initial dosing regimen for buspirone is 5 mg twice daily, which should be gradually increased based on clinical response and tolerability, with a maximum daily dose of 60 mg typically administered in divided doses. 1

Starting Dose and Titration

• Begin with 5 mg twice daily (10 mg/day total) 1
• Gradually increase the dose every 2-3 days based on clinical response and tolerability 1
• Typical maintenance dosage ranges from 15-30 mg/day in divided doses 1, 2
• Maximum recommended daily dose is 60 mg/day, typically administered as 20 mg three times daily 1

Administration Considerations

• Administer in 2-3 divided doses per day (BID or TID) to maintain steady blood levels 3
• A twice-daily (BID) regimen may offer better convenience and potentially higher compliance compared to three times daily (TID) dosing, with similar safety profiles 3
• Taking buspirone with food increases the maximum concentration (Cmax) and bioavailability by approximately 2-fold 4

Expected Timeframe for Efficacy

• Patients should be informed that buspirone may take 2-4 weeks to become effective for anxiety symptoms 1
• Unlike benzodiazepines, buspirone does not provide immediate relief of anxiety symptoms 5
• This "lag time" of 1-2 weeks to onset of anxiolytic effect necessitates counseling patients about the importance of adherence 5

Special Populations

• For elderly patients or those with hepatic impairment, consider starting at a lower dose (2.5 mg twice daily) 2
• In patients with severe hepatic or renal impairment, buspirone is not recommended due to increased plasma levels and lengthened half-life 2
• For patients ≥65 years old, use caution as greater sensitivity cannot be ruled out, although specific pharmacokinetic changes due to age have not been identified 2

Drug Interactions

• Reduce buspirone dose when co-administered with CYP3A4 inhibitors such as:
  • Erythromycin (consider 2.5 mg twice daily) 2
  • Itraconazole (consider 2.5 mg once daily) 2
  • Nefazodone (consider 2.5 mg once daily) 2
  • Diltiazem or verapamil (consider lower doses) 2
• Avoid large amounts of grapefruit juice, which can significantly increase buspirone concentrations 2
• Higher doses of buspirone may be needed when co-administered with CYP3A4 inducers like rifampin, phenytoin, phenobarbital, or carbamazepine 2

Monitoring and Follow-up

• Assess for common side effects including dizziness, headache, and nausea 3
• Monitor for less common side effects such as palpitations, which may be more frequent with twice-daily dosing 3
• Unlike benzodiazepines, buspirone has limited potential for abuse and dependence, and does not typically cause sedation or psychomotor impairment 5
• No withdrawal syndrome has been observed when buspirone is abruptly discontinued, even after more than six months of therapy 6

Clinical Pearls

• Buspirone lacks hypnotic, anticonvulsant, and muscle relaxant properties, making it "anxioselective" compared to benzodiazepines 5
• It does not typically impair psychomotor or cognitive function and appears to have no additive effect with alcohol 5
• Buspirone may be preferred in patients where daytime alertness is particularly important 5
• Periodically reevaluate the need for continued therapy, especially when used for several months or longer 6