What is the appropriate dosing to start gabapentin (Neurontin) for anxiety and depression?

Appropriate Dosing of Gabapentin for Anxiety and Depression

For anxiety and depression, gabapentin should be started at 100-300 mg at bedtime or 100-300 mg three times daily, with gradual titration by 100-300 mg every 1-7 days as tolerated, up to an effective dose typically between 900-1800 mg/day in divided doses. 1

Initial Dosing Strategy

Gabapentin requires careful titration due to its nonlinear pharmacokinetics (saturable absorption). The following approach is recommended:

• Starting dose: 100-300 mg at bedtime or 100-300 mg three times daily
• Titration: Increase by 100-300 mg every 1-7 days as tolerated
• Target dose range: 900-1800 mg/day in divided doses
• Maximum dose: Up to 3600 mg/day in 3 divided doses, though doses above 1800 mg/day may not provide additional benefit for anxiety/depression

Evidence for Anxiety

Research supports gabapentin's efficacy for anxiety at various doses:

• A randomized controlled trial found that both 300 mg and 900 mg daily doses were effective for anxiety symptoms, with the 300 mg dose being sufficient for most patients except those with severe baseline anxiety 2
• Gabapentin 800 mg has been shown to attenuate anxiety in experimental settings 3

Evidence for Depression

For depression, gabapentin is typically used as adjunctive therapy rather than monotherapy:

• In treatment-resistant depression, adjunctive gabapentin at a mean final dose of 904 mg/day (range 300-1800 mg/day) showed benefit in 37% of patients 4
• For patients with bipolar mixed states with depressive features, doses ranging from 600-2000 mg/day (mean 1130 mg/day) were effective 5

Practical Dosing Considerations

• Start low: Beginning with lower doses (100-300 mg) reduces the risk of side effects like dizziness and sedation
• Evening dosing: Initial doses are often better tolerated when given at bedtime
• Divided dosing: As the dose increases, divide into 2-3 daily doses for better tolerability and efficacy
• Duration of trial: An adequate trial requires 3-8 weeks for titration plus 2 weeks at maximum dose 1

Monitoring and Side Effects

• Common side effects: Dizziness, sedation, fatigue, peripheral edema
• Dose-dependent side effects: Higher doses increase risk of adverse effects
• Renal function: Dose adjustment required in patients with renal impairment

Important Caveats

• Gabapentin is FDA-approved for seizures and postherpetic neuralgia, not anxiety or depression
• Systematic reviews indicate variable evidence for gabapentin in psychiatric disorders, with stronger evidence for anxiety disorders than for depression 6
• For patients with both anxiety and depression, combination therapy with an antidepressant may be necessary

Discontinuation

• Gabapentin should not be abruptly discontinued
• When stopping treatment, gradually taper the dose over at least 1 week to avoid withdrawal symptoms

Remember that while gabapentin has shown promise for anxiety symptoms, the evidence for its use in depression is more limited, and it is typically used as an adjunctive treatment rather than monotherapy for mood disorders.