Guidelines for Prescribing Buspirone (BuSpar)
Buspirone should be initiated at 15 mg daily (7.5 mg twice daily) and may be gradually increased by 5 mg every 2-3 days as needed, with a maximum daily dose of 60 mg. 1
Indications and Mechanism of Action
- Primary indication: Treatment of generalized anxiety disorder (GAD)
- Mechanism: Acts primarily through 5-HT1A receptors in the central nervous system 2
- Unlike benzodiazepines, buspirone:
- Lacks anticonvulsant and muscle-relaxant properties
- Causes minimal sedation
- Has no abuse or dependence potential
- Does not produce withdrawal symptoms upon discontinuation
Dosing Protocol
Initial Dosing
- Start with 15 mg daily divided into two doses (7.5 mg twice daily) 1
- For elderly or frail patients: Consider starting with a lower dose (5 mg twice daily) 3
Dose Titration
- Increase dose by 5 mg every 2-3 days based on response and tolerability 1
- Most patients respond to 15-30 mg/day 4
- Maximum recommended dose: 60 mg/day 1
Administration Considerations
- Take consistently with regard to food (either always with or always without food)
- Bioavailability increases approximately 2-fold when taken with food 1, 5
- For mild to moderate agitation in elderly patients, initial dose should be 5 mg twice daily with maximum of 20 mg three times daily 3
Onset of Action and Efficacy
- Important patient education point: Buspirone has a delayed onset of action
- Takes 2-4 weeks to become effective for anxiety symptoms 3
- Not appropriate for immediate relief of acute anxiety
- Efficacy is comparable to benzodiazepines for GAD 2
Drug Interactions
Contraindicated Combinations
- MAO inhibitors: Allow at least 14 days between discontinuing MAOIs and starting buspirone 1
- Linezolid or methylene blue: Risk of serotonin syndrome 1
Dose Adjustment Required
- CYP3A4 inhibitors (verapamil, diltiazem, erythromycin, itraconazole): Significantly increase buspirone levels; reduce buspirone dose 5
- Rifampin: Decreases buspirone plasma concentrations by approximately 10-fold; may require dose increase 5
Special Populations
Hepatic Impairment
- Buspirone concentrations may be 15-fold higher in patients with hepatic impairment
- Half-life doubles in these patients
- Use lower doses and monitor closely 5
Renal Impairment
- Concentrations may be 2-fold higher in patients with renal impairment
- Consider dose reduction 5
Elderly Patients
- Start with lower doses (5 mg twice daily)
- Titrate more slowly
- Monitor for side effects 3
Common Side Effects
- Headaches
- Dizziness
- Nervousness
- Lightheadedness 2
- Nausea
- Insomnia
Duration of Treatment
- Periodic reevaluation of the need for continued therapy is recommended
- Long-term studies have shown safety for up to one year of continuous use 4
- No withdrawal syndrome observed after abrupt discontinuation, even after 6+ months of therapy 4
Clinical Pearls and Pitfalls
Common Pitfalls
- Expecting immediate relief: Buspirone takes 2-4 weeks to become effective; not suitable for acute anxiety relief
- Inadequate trial duration: Full therapeutic effect may require 4-8 weeks
- Inadequate dosing: Some patients require higher doses within the recommended range
- Not accounting for food effects: Inconsistent administration with/without food can lead to variable absorption
When to Consider Alternatives
- When rapid anxiety relief is needed
- For patients with panic disorder (buspirone has limited efficacy) 6
- When sedation is a desired effect (buspirone causes minimal sedation)
By following these guidelines, clinicians can appropriately prescribe buspirone for patients with generalized anxiety disorder while minimizing adverse effects and maximizing therapeutic benefit.