Standard Dosing for Gabapentin in Anxiety
For anxiety treatment, gabapentin should be started at 300 mg once daily, gradually increased to 300 mg three times daily (900 mg/day), with further titration to 1800 mg/day if needed for optimal efficacy. 1
Initial Dosing and Titration
- Starting dose: 300 mg once daily at bedtime
- Titration schedule:
- Day 1: 300 mg once daily
- Day 2: 300 mg twice daily
- Day 3 onward: 300 mg three times daily (900 mg/day total)
- Further increases as needed and tolerated
Target Dosing
- Moderate anxiety: 900 mg/day (divided into three doses)
- Severe anxiety: May require up to 1800 mg/day for optimal effect
- Maximum recommended dose: 3600 mg/day, though doses above 1800 mg/day rarely provide additional benefit for anxiety
Dosing Considerations
Renal Adjustment
Gabapentin requires dose adjustment in renal impairment 1:
| Creatinine Clearance (mL/min) | Total Daily Dose Range (mg/day) | Dose Regimen |
|---|---|---|
| ≥60 | 900-3600 | 300-1200 mg TID |
| >30-59 | 400-1400 | 200-700 mg BID |
| >15-29 | 200-700 | 200-700 mg QD |
| ≤15 | 100-300 | 100-300 mg QD |
Special Populations
- Elderly patients: Start with lower doses (100-300 mg daily) and titrate more slowly to minimize side effects, particularly sedation and dizziness 1
- Women of reproductive potential: Counseling regarding contraception is recommended as gabapentin is not recommended during pregnancy 1
Efficacy Evidence
Research supports gabapentin's efficacy for anxiety:
- In breast cancer survivors, both 300 mg and 900 mg doses showed significant improvement in anxiety compared to placebo, with the 300 mg dose being effective for most patients except those with severe baseline anxiety 2
- For preoperative anxiety, gabapentin 1200 mg significantly reduced anxiety scores and pain catastrophizing compared to placebo 3
- In simulated public speaking anxiety, 800 mg of gabapentin showed anxiolytic effects 4
- A meta-analysis found moderate evidence supporting gabapentin's efficacy in anxiety states with standardized mean differences ranging from -0.92 to -0.52 compared to placebo 5
Monitoring and Side Effects
- Common side effects: Somnolence, dizziness, headache, and fatigue
- Monitoring: Assess for excessive sedation, particularly when initiating therapy or increasing doses
- Drug interactions: Minimal drug interactions as gabapentin is not metabolized by the liver and does not affect cytochrome P450 enzymes
Clinical Advantages
- Gabapentin may be particularly useful for patients with:
Treatment Duration
- For acute anxiety: 4-8 weeks trial to assess efficacy
- For chronic anxiety: Regular reassessment of continued benefit versus side effects
- Long-term treatment (>12 months) is justified in patients who maintain benefit with minimal side effects 1