What is the recommended dosage and treatment plan for gabapentin (Neurontin) in managing seizures?

Gabapentin Dosing for Seizure Management

For adult patients with epilepsy and partial onset seizures, gabapentin should be initiated at 300 mg three times daily with a recommended maintenance dose of 300-600 mg three times daily, with total daily doses up to 2400 mg well-tolerated in long-term clinical studies. 1

Adult Dosing Protocol

• Initial dosing: Start with 300 mg three times daily 1
• Maintenance dosing: 300-600 mg three times daily (900-1800 mg/day) 1
• Maximum dosing: Doses up to 2400 mg/day have been well-tolerated in long-term clinical studies, and doses up to 3600 mg/day have been administered for shorter durations with good tolerability 1, 2
• Dosing interval: The maximum time between doses should not exceed 12 hours to maintain therapeutic levels 1

Pediatric Dosing (Ages 3-11)

• Ages 3-4 years: Starting dose of 10-15 mg/kg/day in three divided doses, with a recommended maintenance dose of 40 mg/kg/day 1
• Ages 5-11 years: Starting dose of 10-15 mg/kg/day in three divided doses, with a recommended maintenance dose of 25-35 mg/kg/day 1
• Maximum pediatric dose: Dosages up to 50 mg/kg/day have been well-tolerated in long-term clinical studies 1

Dosage Adjustment for Renal Impairment

• Normal renal function (CrCl ≥60 mL/min): 300-1200 mg three times daily 1
• Moderate impairment (CrCl 30-59 mL/min): 200-700 mg twice daily 1
• Severe impairment (CrCl 15-29 mL/min): 200-700 mg once daily 1
• Very severe impairment (CrCl <15 mL/min): 100-300 mg once daily 1
• Hemodialysis patients: Require supplemental post-hemodialysis doses 1

Titration Recommendations

• Standard titration can begin at 300 mg three times daily, but clinical evidence suggests improved seizure control with higher maintenance doses without significant increases in adverse effects 2
• For most adult patients, gabapentin may be initiated at 900 mg/day and titrated to maintenance doses ≥3600 mg/day based on individual response 2
• Rapid initiation (starting at 900 mg/day) has shown similar tolerability to slower titration schedules in clinical studies 3, 2

Efficacy Considerations

• Gabapentin is indicated as adjunctive therapy for partial seizures with or without secondary generalization in patients 12 years and older 1, 4
• Studies have demonstrated long-term efficacy with no systematic evidence of tolerance development 4
• Higher doses (>1800 mg/day) may provide better seizure control in patients with more refractory seizures 5
• In a study of 1055 evaluable patients, 76% achieved at least a 50% reduction in seizure frequency, and 46.4% became seizure-free with gabapentin as adjunctive therapy 5

Safety and Monitoring

• Gabapentin has a broad therapeutic index, allowing for dose adjustments based on individual patient needs 4
• Most common adverse effects include somnolence, dizziness, ataxia, and fatigue 1, 6
• Side effects typically occur around the onset of dosing and may be transient 2
• Gabapentin has few clinically significant drug-drug interactions 4

Important Considerations

• Gabapentin should not be discontinued abruptly; gradual tapering over at least 1 week is recommended to avoid withdrawal seizures 1
• For patients requiring divided tablets, unused half-tablets should be taken as the next dose and discarded if not used within 28 days 1
• Elderly patients may require dose adjustments based on creatinine clearance values due to age-related decreases in renal function 1

Comparative Efficacy

• For status epilepticus, gabapentin is not a first-line agent; fosphenytoin, levetiracetam, or valproate are recommended for seizures refractory to benzodiazepines 3
• For routine seizure management, gabapentin has shown efficacy as both adjunctive therapy and monotherapy for partial seizures 4, 7