What is the dose of gabapentin (GABA analog) for anxiety in adults?

Gabapentin Dosing for Anxiety in Adults

For anxiety in adults, gabapentin should be started at 300 mg at bedtime or 100-300 mg three times daily, with gradual titration to an effective dose of 900-1800 mg/day in divided doses, which provides optimal benefit with minimal side effects. 1

Initial Dosing and Titration

• Start with 100-300 mg at bedtime or 100-300 mg three times daily
• Gradually increase by 300 mg every 1-3 days as tolerated
• Take with food to improve tolerability
• Divide daily dose into three administrations to minimize side effects

Target Dosing Range

• Effective dose range: 900-1800 mg/day (divided into 3 doses)
• Research supports efficacy of lower doses for anxiety:
  • 300 mg daily was effective for anxiety in breast cancer survivors 2
  • 800 mg daily showed anxiolytic effects in simulated public speaking anxiety 3

Maximum Dosing

• Maximum dose: 3600 mg/day (1200 mg three times daily)
• Doses above 1800 mg/day provide minimal additional benefit while significantly increasing adverse effects 1
• Higher doses (2400-3600 mg/day) should be reserved for severe cases that don't respond to lower doses

Dosing Considerations for Special Populations

• Elderly patients: Start at lower doses (100 mg at bedtime) and titrate more slowly
• Renal impairment: Dose adjustment required based on creatinine clearance
  • CrCl 30-59 mL/min: maximum 700 mg twice daily
  • CrCl 15-29 mL/min: maximum 700 mg once daily
  • CrCl <15 mL/min: maximum 300 mg once daily

Monitoring and Assessment

• Allow 3-8 weeks for titration plus 2 weeks at maximum dose before assessing efficacy 1
• Monitor for common adverse effects:
  • Dizziness (19% of patients)
  • Somnolence (14%)
  • Peripheral edema (7%)
  • Gait disturbance (14%)

Clinical Evidence for Anxiety

• Randomized controlled trials have shown gabapentin to be effective for anxiety at doses ranging from 300-900 mg/day 2
• More severely ill patients with panic disorder showed significant improvement with gabapentin (600-3600 mg/day) 4
• Gabapentin at 800 mg attenuated anxiety in simulated public speaking 3

Discontinuation

• When discontinuing, taper gradually over at least 1 week to avoid withdrawal symptoms
• Recommended tapering schedule:
  • Reduce by 300 mg every 3-7 days
  • More gradual tapering may be needed for patients on higher doses

Important Considerations

• Gabapentin is not FDA-approved for anxiety but is commonly used off-label
• Lower doses (900-1800 mg/day) offer the best balance of efficacy and tolerability for most patients 1
• Gabapentin may be particularly useful for patients with comorbid neuropathic pain or those who should avoid benzodiazepines 2