Buspirone 15mg TID for Anxiety: Dosing Assessment
Buspirone 15mg three times daily (45 mg/day total) is an appropriate and commonly used therapeutic dose for generalized anxiety disorder, falling well within the recommended range of 15-60 mg/day. 1
Standard Dosing Protocol
The American Academy of Family Physicians recommends the following titration schedule for buspirone 1:
- Initial dose: 5 mg twice daily (10 mg/day total) 1
- Titration: Increase by 5 mg per day every 2-3 days until therapeutic effect is achieved 1
- Target therapeutic range: 15-30 mg/day divided into 2-3 doses 1
- Maximum dose: 60 mg/day (can be given as 20 mg three times daily) 1
Your current regimen of 15 mg TID (45 mg/day) is within the therapeutic range and represents a higher-end dose that may be appropriate for patients requiring more robust anxiolytic effect. 1
Dosing Frequency Considerations
While 15 mg TID is effective, a twice-daily regimen may offer equivalent efficacy with improved convenience and compliance. 2 A meta-analysis of 289 patients demonstrated that buspirone 15 mg BID (30 mg/day) had similar safety and tolerability to 10 mg TID (30 mg/day), with no compromise in anxiolytic effect. 2 The only significant difference was a slightly higher incidence of palpitations with BID dosing (5% vs 1%). 2
If you are currently taking 45 mg/day, this could be restructured as:
- Option 1: Continue 15 mg TID (current regimen) 1
- Option 2: Consider 22.5 mg BID for improved convenience, though this would require splitting tablets 2
Timeline for Therapeutic Effect
A critical caveat: buspirone requires 1-2 weeks to demonstrate anxiolytic effect, unlike benzodiazepines which work immediately. 3 Patient motivation and compliance during this "lag time" is essential. 3 If you have been on this dose for less than 2 weeks, continue the regimen before assessing efficacy. 3
Safety Profile at This Dose
At 45 mg/day, buspirone maintains an excellent safety profile 1, 2:
- Most common side effects: Dizziness, headache, nausea, nervousness, and lightheadedness 2, 4
- No sedation, muscle relaxation, or anticonvulsant effects (unlike benzodiazepines) 4, 3
- No psychomotor impairment when combined with alcohol or given alone 4
- No abuse potential, dependence, or withdrawal symptoms reported 4, 5
- No cognitive impairment in healthy volunteers 3, 5
Special Population Adjustments
Elderly patients: Standard dosing is appropriate, but monitor more carefully for side effects, starting with 5 mg BID. 1 Pharmacokinetic studies show no age-related differences in buspirone metabolism. 6
Hepatic or renal impairment: Buspirone is contraindicated in severe hepatic or renal dysfunction, as plasma levels increase substantially and half-life is prolonged. 6, 7 In hepatic impairment, Cmax and AUC increase 15-fold with a doubled half-life. 7 In renal impairment, Cmax and AUC double. 7
Drug Interactions to Monitor
Avoid or use with extreme caution 6, 7:
- CYP3A4 inhibitors (verapamil, diltiazem, erythromycin, itraconazole) substantially increase buspirone plasma concentrations 7
- Rifampin decreases buspirone concentrations nearly 10-fold 7
- Warfarin: One case report of prolonged prothrombin time when buspirone was added 6
Minimal interaction with cimetidine, alprazolam, alcohol, and other CNS-active agents. 7, 5
Food Effects
Take buspirone consistently with or without food. 7 Food increases Cmax and AUC 2-fold, so switching between fed and fasted states may cause variable drug levels. 7
Clinical Advantages Over Benzodiazepines
Buspirone is particularly appropriate when 4, 3, 5:
- Daytime alertness is critical (no sedation) 3, 5
- Long-term therapy is anticipated (no dependence risk) 4, 5
- Driving or operating machinery is required (no psychomotor impairment) 3, 5
- Alcohol use is a concern (no additive CNS depression) 4, 5
The 15 mg TID regimen is appropriate, safe, and within standard therapeutic guidelines for generalized anxiety disorder. 1, 2