Buspirone Dosing for Adults with Anxiety
Start buspirone at 5 mg twice daily (10 mg/day total) and increase by 5 mg/day every 2-3 days until reaching the target dose of 15-30 mg/day divided into 2-3 doses, with a maximum of 60 mg/day. 1
Standard Dosing Algorithm
Initial dose: 5 mg orally twice daily 1, 2
Titration schedule: Increase by 5 mg/day every 2-3 days based on response and tolerability 1
Target therapeutic dose: 15-30 mg/day in divided doses (typically 7.5-15 mg twice daily) 1, 3, 4
Maximum dose: 60 mg/day (20 mg three times daily) 1, 2
Critical Timing Consideration
Buspirone requires 2-4 weeks to achieve full anxiolytic effect, which is essential for patient counseling to prevent premature discontinuation 1. Some studies note a "lag time" of 1-2 weeks before onset of anxiolytic effect, necessitating patient motivation and compliance support 4.
Food Effects on Bioavailability
Taking buspirone with food increases both peak concentration (Cmax) and area under the curve (AUC) by approximately 84-116%, suggesting food decreases presystemic clearance 2. This represents a clinically significant interaction that should be considered for consistent dosing.
Hepatic Impairment
Buspirone is contraindicated in severe hepatic impairment. 2
- Steady-state AUC increases 13-fold in patients with hepatic impairment compared to healthy subjects 2
- Elimination half-life doubles in hepatic impairment 5
- The FDA label explicitly states that administration to patients with severe hepatic impairment cannot be recommended 2
- Plasma clearance is reduced in hepatic cirrhosis 3
Renal Impairment
Buspirone is contraindicated in severe renal impairment. 2
- Steady-state AUC increases 4-fold in renally impaired patients (creatinine clearance 10-70 mL/min/1.73 m²) compared to healthy subjects 2
- After a single 20 mg dose, Cmax and AUC increase 2-fold in patients with renal impairment 5
- The FDA label states that administration to patients with severe renal impairment cannot be recommended 2
- Reduced plasma clearance occurs in renal impairment 3
Elderly Patients
Elderly patients can start at the standard dose of 5 mg twice daily with no age-based dose adjustment required. 1
- Pharmacokinetic studies show no significant differences in buspirone AUC and Cmax between elderly and younger subjects 2
- A controlled trial in patients over 65 years demonstrated efficacy at a mean dose of 18 mg/day, similar to doses used in younger patients 6
- Buspirone was well tolerated in elderly patients receiving concomitant treatment for chronic medical conditions 6
- The safety and efficacy profiles for 605 elderly patients (mean age 70.8 years) were similar to younger populations 2
Common Pitfalls to Avoid
Do not discontinue prematurely: The 2-4 week delay in therapeutic effect means patients may perceive lack of efficacy if assessed too early 1, 4
Monitor for drug interactions: Buspirone is metabolized by CYP3A4, and coadministration with verapamil, diltiazem, erythromycin, or itraconazole substantially increases buspirone plasma concentrations, while rifampin decreases concentrations almost 10-fold 5
Avoid in benzodiazepine withdrawal: Buspirone is not effective for treating benzodiazepine withdrawal symptoms 3
Consider food timing: Inconsistent administration with or without food can lead to variable plasma levels 2