Starting Dose of Buspar (Buspirone) for Adult Anxiety
Start buspirone at 5 mg twice daily (total 10 mg/day) for most adult patients with generalized anxiety disorder, then increase by 5 mg every 2-3 days as tolerated to reach the therapeutic range of 15-30 mg/day. 1, 2
Initial Dosing Algorithm
- Begin with 5 mg twice daily (BID) as the standard starting dose for adult patients 1, 2
- An alternative starting approach of 7.5 mg twice daily exists, but the 5 mg BID dose is more commonly recommended in current guidelines 1
- Take the second dose earlier in the day rather than late evening to minimize insomnia risk 3
Titration Schedule
- Increase dosage by 5 mg increments every 2-3 days based on patient tolerance and response 1, 2
- Target the therapeutic range of 15-30 mg/day in divided doses for optimal efficacy 1, 2
- Maximum dose is 60 mg/day (20 mg three times daily), though this is rarely needed 1, 2
Special Population Adjustments
- Elderly or debilitated patients: Start at lower doses of 2.5-5 mg twice daily and titrate more gradually, as this population demonstrates increased sensitivity to medication effects 1
- Hepatic impairment: Exercise significant caution, as buspirone concentrations increase 15-fold in hepatic impairment with doubled half-life 4
- Renal impairment: Expect 2-fold increases in peak concentration and drug exposure 4
Critical Timing Expectations
- Full therapeutic effect requires 2-4 weeks minimum before assessing efficacy 2
- Some studies note a "lagtime" of 1-2 weeks before anxiolytic effects become apparent 5
- Do not discontinue prematurely before the 2-4 week therapeutic window 2
- Buspirone is inappropriate for acute anxiety requiring immediate relief 2
Common Prescribing Pitfalls to Avoid
- Avoid starting at too high a dose, which increases side effects without providing faster benefit 2
- Do not assess response before 2-4 weeks, as premature evaluation leads to inappropriate discontinuation 2
- Buspirone is only useful in mild-to-moderate anxiety, not effective for severe agitation or acute panic 2
- Previous benzodiazepine exposure may reduce buspirone efficacy, as patients accustomed to immediate benzodiazepine effects may not tolerate the delayed onset 6
Drug Interactions Affecting Dosing
- CYP3A4 inhibitors (verapamil, diltiazem, erythromycin, itraconazole) substantially increase buspirone plasma concentrations and may require dose reduction 4
- Rifampin decreases buspirone concentrations nearly 10-fold, requiring dose increases if co-administered 4
- Food increases buspirone absorption 2-fold, so consistent administration timing relative to meals is important 4