What is the recommended dosing for Buspar (buspirone) in adults with anxiety, considering factors such as age, hepatic or renal impairment, and history of substance abuse?

Buspar (Buspirone) Dosing for Adults with Anxiety

Start buspirone at 5 mg twice daily (10 mg/day total) and titrate upward by 5 mg/day every 2-3 days as tolerated, with a typical target dose of 15-30 mg/day divided into 2-3 doses, and a maximum of 60 mg/day. 1, 2

Standard Dosing Algorithm

Initial Dosing

• Starting dose: 5 mg orally twice daily 1
• Titration schedule: Increase by 5 mg/day every 2-3 days based on response and tolerability 2, 3
• Target therapeutic dose: 15-30 mg/day in divided doses (typically 7.5-15 mg twice daily) 1, 4, 5
• Maximum dose: 60 mg/day (20 mg three times daily) 1

Key Dosing Considerations

Onset of action: Buspirone requires 2-4 weeks to achieve full anxiolytic effect 1, 6. This delayed onset is critical for patient counseling—unlike benzodiazepines, buspirone does not provide immediate relief, and patients must be motivated to continue therapy during this lag period 6, 4.

Food effects: Administration with food increases bioavailability by approximately 84% (AUC) and peak concentrations by 116% 2, 3. For consistent dosing, administer buspirone the same way each time—either always with food or always without food 2.

Special Populations

Elderly Patients

• Use standard adult dosing: Start at 5 mg twice daily 1, 5
• No dose adjustment needed based on age alone—pharmacokinetics are similar between elderly and younger adults 2
• Mean effective dose in elderly patients is approximately 18 mg/day 5
• Elderly patients tolerate buspirone well, even when receiving multiple concomitant medications for chronic conditions 5

Hepatic Impairment

• Severe hepatic impairment: Buspirone is contraindicated 2
• Steady-state AUC increases 13-fold in hepatic impairment compared to healthy subjects 2
• Half-life doubles in patients with hepatic disease 3
• If mild-moderate impairment, use lowest effective doses with careful titration and monitoring 2

Renal Impairment

• Severe renal impairment (CrCl <30 mL/min): Buspirone is contraindicated 2
• Steady-state AUC increases 4-fold in renal impairment (CrCl 10-70 mL/min/1.73 m²) 2
• Peak concentrations and AUC double after single 20 mg dose in renal impairment 3
• For mild-moderate impairment, reduce initial dose and titrate cautiously 2

Substance Abuse History

• Buspirone has minimal abuse potential and does not produce dependence 4, 7
• Does not cause withdrawal symptoms upon discontinuation 6, 4
• Does not potentiate alcohol or other sedative-hypnotics 4, 7
• Preferred anxiolytic in patients with substance use disorders due to lack of reinforcing properties 6, 4
• No cross-tolerance with benzodiazepines—cannot be used for benzodiazepine withdrawal 7

Clinical Pearls and Pitfalls

Common Pitfalls to Avoid

• Do not expect immediate relief: Patients accustomed to benzodiazepines may discontinue prematurely due to 1-2 week lag time to therapeutic effect 6, 4
• Do not use for panic disorder: Evidence for buspirone in panic disorder is inconclusive and it is not recommended for this indication 6
• Do not use for acute anxiety or PRN dosing: Buspirone requires chronic administration for efficacy 6, 7
• Monitor for drug interactions: CYP3A4 inhibitors (erythromycin, itraconazole, verapamil, diltiazem) substantially increase buspirone levels, while rifampin decreases levels 10-fold 3

Optimal Patient Selection

• Best candidates: Patients with generalized anxiety disorder, chronic anxiety, elderly patients, and those with mixed anxiety-depression 6, 5
• Particularly appropriate for: Patients who cannot tolerate sedation, those requiring daytime alertness, and patients with substance abuse history 6, 4
• Less suitable for: Patients demanding immediate relief or those with panic disorder 6

Pharmacokinetic Considerations

• Extensive first-pass metabolism: Absolute bioavailability is only 4% 3
• Short half-life: Approximately 2-3 hours, necessitating multiple daily doses 2, 3
• No accumulation: After 9 days of 10 mg/day dosing, no accumulation of parent drug or active metabolite (1-PP) occurs 3
• Linear pharmacokinetics: Dose-proportional over 10-40 mg range 3