What is the recommended starting dose of Buspar (buspirone) for a patient already taking 15mg of Lexapro (escitalopram)?

Starting Dose of Buspirone for a Patient on 15mg Lexapro

Start buspirone at 7.5 mg twice daily (15 mg total daily dose) and increase by 5 mg per day every 2-3 days as needed, up to a maximum of 60 mg daily. 1

Initial Dosing Strategy

• The FDA-approved starting dose is 15 mg daily, administered as 7.5 mg twice daily. 1
• The dose may be increased by 5 mg per day at intervals of 2-3 days to achieve optimal therapeutic response. 1
• Most patients in clinical trials were successfully managed on divided doses of 20-30 mg per day. 1, 2
• The maximum daily dose should not exceed 60 mg per day. 3, 1

Critical Timing and Administration Considerations

• Buspirone must be taken consistently with regard to food—either always with food or always without food—because food increases bioavailability approximately 2-fold. 1, 4
• The medication requires 2-4 weeks to become effective for anxiety symptoms, so patients should be counseled about delayed onset of action. 3
• When combining with escitalopram (Lexapro), there are no specific dose adjustments required for buspirone, as no significant pharmacokinetic interactions exist between SSRIs and buspirone. 1

Drug Interaction Screening

• Verify the patient is not taking MAOIs—at least 14 days must elapse between discontinuing an MAOI and starting buspirone, and vice versa. 1
• Screen for potent CYP3A4 inhibitors (verapamil, diltiazem, erythromycin, itraconazole), which can substantially increase buspirone plasma concentrations and may require dose reduction. 1, 4
• Rifampin decreases buspirone concentrations nearly 10-fold, potentially requiring dose increases if co-administered. 4

Practical Dosing Algorithm

Week 1:

• Start 7.5 mg twice daily (morning and evening). 1

Week 1-2 (Days 3-7):

• If tolerated but insufficient response, increase to 10 mg twice daily (20 mg total). 1

Week 2-3:

• If needed, increase to 15 mg twice daily (30 mg total)—this is the most commonly employed dose in clinical trials. 1, 2

Beyond Week 3:

• Continue titrating by 5 mg per day every 2-3 days up to maximum 60 mg daily if clinically indicated. 1

Safety Considerations with Escitalopram Combination

• The combination of buspirone and SSRIs like escitalopram is well-established and commonly used for augmentation in treatment-resistant depression or anxiety. 5
• Buspirone augmentation of SSRIs has been shown to reduce depression severity more effectively than other augmentation strategies in some studies. 5
• Monitor for serotonin syndrome symptoms, though the risk is low with this combination at standard doses. 1
• Both medications are generally well-tolerated together without significant additive side effects. 6, 7

Common Pitfalls to Avoid

• Do not discontinue buspirone prematurely before 2-4 weeks of adequate dosing—patients may abandon therapy before therapeutic effects emerge. 3
• Avoid inconsistent administration with respect to food, as this creates variable plasma concentrations and unpredictable efficacy. 1, 4
• Do not exceed 60 mg daily, as higher doses have not been studied and may increase adverse effects without additional benefit. 3, 1
• Remember that buspirone lacks the immediate anxiolytic effects of benzodiazepines and requires patient education about delayed onset. 3, 6

Monitoring Parameters

• Assess therapeutic response at 2-4 weeks after reaching target dose. 3
• Monitor for common side effects including dizziness, headache, nausea, and lightheadedness. 6, 7
• The incidence of adverse events is generally low, and buspirone has no abuse potential or withdrawal syndrome. 6, 2