What is the recommended use and dosage of Gabapentin (Neurontin) for treating nerve pain and epilepsy?

Gabapentin Dosing for Nerve Pain and Epilepsy

For neuropathic pain, gabapentin should be started at 100-300 mg at bedtime or 300 mg three times daily, gradually titrated to an effective dose of 900-3600 mg/day in divided doses, with most patients requiring 1800-3600 mg/day for optimal pain relief. 1, 2, 3

Dosing for Neuropathic Pain

Initial Dosing and Titration

• Start with 100-300 mg at bedtime or 100-300 mg three times daily 1
• Increase by 100-300 mg every 1-7 days as tolerated 1
• Aim for a total daily dose of 1800-3600 mg/day in 3 divided doses 1, 3
• An adequate trial requires 2 months or more for full effect assessment 1
• Slower titration is recommended for elderly patients and those with renal impairment 1, 2

Maximum Effective Dose

• Maximum recommended dose is 3600 mg/day in 3 divided doses 2
• Clinical studies show efficacy across 1800-3600 mg/day, with most patients requiring at least 1800 mg/day for adequate pain relief 3
• The maximum time between doses should not exceed 12 hours 2

Dosing for Epilepsy

Adults and Children 12 Years and Older

• Starting dose: 300 mg three times daily 2
• Recommended maintenance dose: 300-600 mg three times daily 2
• Dosages up to 2400 mg/day have been well-tolerated in long-term studies 2
• Doses of 3600 mg/day have been administered for shorter durations with good tolerability 2

Children 3-11 Years

• Starting dose: 10-15 mg/kg/day in three divided doses 2
• Maintenance dose for ages 3-4 years: 40 mg/kg/day in three divided doses 2
• Maintenance dose for ages 5-11 years: 25-35 mg/kg/day in three divided doses 2
• Maximum time between doses should not exceed 12 hours 2

Dosage Adjustment for Renal Impairment

• Creatinine clearance ≥60 mL/min: 900-3600 mg/day (300-1200 mg TID) 2
• Creatinine clearance 30-59 mL/min: 400-1400 mg/day (200-700 mg BID) 2
• Creatinine clearance 15-29 mL/min: 200-700 mg/day (200-700 mg QD) 2
• Creatinine clearance <15 mL/min: 100-300 mg/day (100-300 mg QD) 2
• Hemodialysis patients require supplemental doses after each 4-hour hemodialysis session 2

Administration Guidelines

• Gabapentin can be administered with or without food 2
• If using scored tablets (600 mg or 800 mg), unused half-tablets should be taken as the next dose 2
• Half-tablets not used within 28 days should be discarded 2
• When discontinuing gabapentin, taper gradually over at least 1 week to minimize withdrawal symptoms 2

Special Considerations

• Elderly patients are more likely to have decreased renal function and may require lower doses 2
• Gabapentin has nonlinear pharmacokinetics due to saturable absorption, requiring careful titration 1
• Common side effects include dizziness and sedation, which can be reduced by starting with lower doses and titrating slowly 1
• Gabapentin has few drug interactions, making it suitable for patients on multiple medications 1, 2
• For neuropathic pain, gabapentin is often used as a co-analgesic in combination with opioids 1

Clinical Pearls

• Gabapentin's mechanism of action in neuropathic pain involves binding to α2δ-1 subunits of voltage-gated calcium channels 4
• Beyond epilepsy and neuropathic pain, gabapentin has shown efficacy in other conditions including postherpetic neuralgia, diabetic neuropathy, and trigeminal neuralgia 5
• The full therapeutic effect may take weeks to develop, so patients should be counseled about the importance of adherence despite initial lack of efficacy 3
• Side effects are typically mild to moderate and often subside within approximately 10 days of treatment initiation 3