What is the recommended starting dose of Buspar (buspirone) for an adult patient with anxiety?

Starting Dose for Buspar (Buspirone)

Start buspirone at 7.5 mg twice daily (15 mg/day total), then increase by 5 mg/day every 2-3 days as needed to reach the therapeutic range of 15-30 mg/day in divided doses. 1

Initial Dosing Algorithm

• Begin with 7.5 mg twice daily (15 mg/day total) as the FDA-approved starting dose 1
• The American Academy of Family Physicians alternatively recommends starting at 5 mg twice daily, which may be preferable in patients concerned about tolerability 2
• Titrate upward by 5 mg/day increments every 2-3 days based on response and tolerability 2, 1
• Target a therapeutic dose of 15-30 mg/day in divided doses for most patients 2, 1
• Maximum dose is 60 mg/day, though this is rarely needed 2, 1

Critical Timing Expectations

• Buspirone requires 2-4 weeks for full therapeutic effect, making it inappropriate for acute anxiety requiring immediate relief 2
• Do not assess response or discontinue before 2-4 weeks of treatment, as premature discontinuation is a common prescribing error 2
• Some studies note a "lag time" of 1-2 weeks before anxiolytic effects begin, so patient motivation and compliance counseling is essential 3

Food and Administration Considerations

• Take buspirone consistently either always with food or always without food, as food increases bioavailability approximately 2-fold 1, 4
• Consider taking the second daily dose earlier in the day rather than late evening to minimize insomnia risk 2

Special Population Adjustments

Elderly Patients

• Use the standard adult dosing regimen (mean effective dose 18 mg/day, range 5-30 mg/day) in elderly patients, as buspirone is well-tolerated and preferred over benzodiazepines due to lack of sedation, cognitive impairment, and fall risk 2, 5
• Elderly patients in clinical trials tolerated buspirone well even when taking multiple concomitant medications for chronic conditions 5

Hepatic or Renal Impairment

• Reduce dose substantially in hepatic impairment, as buspirone concentrations increase 15-fold and half-life doubles in these patients 4
• Reduce dose in severe renal impairment, as concentrations increase 2-fold 4

Common Prescribing Pitfalls to Avoid

• Do not start at too high a dose, as this increases side effects without providing faster benefit 2
• Do not use buspirone for severe agitation or acute panic—it is only effective for mild-to-moderate generalized anxiety 2
• Do not combine with MAOIs—allow at least 14 days between discontinuing an MAOI and starting buspirone, and vice versa 1
• Avoid combining with strong CYP3A4 inhibitors (erythromycin, itraconazole, verapamil, diltiazem) without dose reduction, as these increase buspirone levels substantially 1, 4

Drug Interactions Requiring Dose Adjustment

• Rifampin decreases buspirone levels nearly 10-fold; higher doses may be needed 4
• Strong CYP3A4 inhibitors increase buspirone levels significantly; reduce buspirone dose when co-administered 1, 4
• Cimetidine and alprazolam have negligible effects on buspirone pharmacokinetics 4