Buspar (Buspirone) Dosing for Adults with Anxiety
Start buspirone at 7.5 mg twice daily (15 mg/day total) and titrate to 20-30 mg daily in divided doses for most patients, with a maximum of 60 mg/day if needed for therapeutic response. 1, 2
Standard Dosing Protocol
Initial Dosing
- Begin with 7.5 mg twice daily (15 mg/day total) 2
- Alternative starting dose of 5 mg twice daily may be used in elderly or frail patients 3
- Increase by 5 mg/day every 2-3 days as tolerated 2
Target Therapeutic Dose
- Most patients require 20-30 mg daily in divided doses for anxiolytic efficacy 1, 4
- The FDA label supports dosing up to 60 mg/day in divided doses 2
- Maximum dose is 60 mg/day (20 mg three times daily) 3
Critical Timing Consideration
- Buspirone requires 2-4 weeks at therapeutic doses to demonstrate full anxiolytic effects 3, 1
- This delayed onset necessitates patient counseling to maintain compliance during the initial weeks 5
Special Population Adjustments
Hepatic Impairment
- Avoid buspirone in severe hepatic impairment 2
- Steady-state AUC increases 13-fold in hepatic impairment compared to healthy subjects 2
- Half-life doubles in hepatic impairment 6
- If use is unavoidable, start with 2.5 mg twice daily and titrate very cautiously 2
Renal Impairment
- Use with extreme caution in severe renal impairment (CrCl <30 mL/min) 2
- Steady-state AUC increases 4-fold in renal impairment (CrCl 10-70 mL/min/1.73 m²) 2
- Consider starting at 5 mg twice daily and monitor closely 2
Elderly Patients
- Start at 5 mg twice daily in patients ≥65 years 3
- Pharmacokinetics are not significantly altered by age, but lower starting doses reduce risk 2, 7
- Mean effective dose in elderly patients was 18 mg/day in controlled trials 7
- Elderly patients tolerate buspirone well at doses similar to younger adults 7
Substance Abuse History
- Buspirone is preferred in patients with substance abuse history 5, 8
- No evidence of dependence, abuse potential, or withdrawal syndrome even after abrupt discontinuation following long-term use 4, 8
- Does not potentiate alcohol or other sedative-hypnotics 5, 8
Important Drug Interactions
CYP3A4 Interactions
- Strong CYP3A4 inhibitors (verapamil, diltiazem, erythromycin, itraconazole) substantially increase buspirone levels 1, 6
- Reduce buspirone dose by 50% or more when combined with strong CYP3A4 inhibitors 1
- Rifampin decreases buspirone levels nearly 10-fold; avoid this combination 6
Food Effects
- Food increases buspirone AUC and Cmax by 84% and 116%, respectively 2
- Administer consistently with or without food to maintain stable plasma levels 2
Dosing Administration
Divided Dosing Schedule
- Administer in 2-3 divided doses throughout the day 1, 2
- Typical schedules: 7.5 mg BID, 10 mg TID, or 15 mg BID 1, 4
- Elimination half-life is only 2-3 hours, necessitating multiple daily doses 2, 6
Duration of Therapy
- Long-term use up to 52 weeks is safe with no new adverse effects emerging 4
- Reassess need for continued therapy after 9 months 3
- No withdrawal syndrome occurs with abrupt discontinuation, even after prolonged use 4
Common Pitfalls to Avoid
- Do not expect immediate anxiolytic effect—counsel patients about the 1-2 week lag time to avoid premature discontinuation 3, 1, 5
- Do not underdose—many patients are maintained on subtherapeutic doses of 10-15 mg/day when they require 20-30 mg/day 1
- Do not use in patients requiring immediate anxiety relief—buspirone is not appropriate for acute anxiety or panic attacks 8
- Discontinue 48 hours before urine catecholamine testing—buspirone interferes with metanephrine assays, causing false-positive results for pheochromocytoma 2