Gabapentin Dosing for Post-Herpetic Neuralgia
For post-herpetic neuralgia, gabapentin should be initiated at 100-300 mg at bedtime or 100-300 mg three times daily, then titrated up to 1800-3600 mg/day in 3 divided doses over 3-8 weeks. 1
Initial Dosing and Titration Schedule
According to the Mayo Clinic guidelines and FDA labeling, the recommended dosing strategy for gabapentin in post-herpetic neuralgia is:
- Day 1: Start with 300 mg as a single dose
- Day 2: Increase to 600 mg/day (300 mg twice daily)
- Day 3: Increase to 900 mg/day (300 mg three times daily)
- Subsequent titration: Gradually increase by 100-300 mg every 1-7 days as tolerated 1, 2
Target Dose Range
The effective dose range for gabapentin in post-herpetic neuralgia is:
- Minimum effective dose: 1800 mg/day
- Maximum dose: 3600 mg/day
- Typical maintenance dose: 1800-2400 mg/day in 3 divided doses 1, 2
Clinical studies have demonstrated efficacy across the 1800-3600 mg/day range, but additional benefit beyond 1800 mg/day was not clearly demonstrated in clinical trials 2.
Administration Considerations
- Administer gabapentin with or without food
- Capsules should be swallowed whole with water
- Maximum time between doses should not exceed 12 hours 2
- Duration of adequate trial: 3-8 weeks for titration plus 2 weeks at maximum dose 1
Dosage Adjustment for Special Populations
Elderly Patients
- Consider lower starting doses and slower titration in geriatric patients
- Elderly patients are more likely to have decreased renal function, requiring dose adjustment 1, 2
Renal Impairment
- Dose adjustment is necessary for patients with compromised renal function
- Base dose on creatinine clearance values 2
Efficacy and Safety Considerations
Gabapentin has demonstrated efficacy for post-herpetic neuralgia with a number needed to treat (NNT) of 4.39 1. The most common adverse effects include:
- Somnolence (reported in up to 80% of patients)
- Dizziness (23.9%)
- Ataxia (7.1%) 3
Alternative Formulations
Extended-release formulations of gabapentin may offer advantages:
- Once-daily dosing may improve adherence
- May provide more consistent plasma levels
- May reduce adverse effects due to peak plasma concentrations 3, 4
However, the standard immediate-release formulation remains the most widely studied and recommended option for post-herpetic neuralgia 1.
Important Clinical Considerations
- If discontinuing gabapentin, taper gradually over at least 1 week to minimize withdrawal symptoms 2
- Gabapentin is considered a first-line oral treatment for neuropathic pain associated with post-herpetic neuralgia 1
- An adequate trial requires sufficient time (at least 3-8 weeks) to determine efficacy 1
- If gabapentin is ineffective or poorly tolerated, consider pregabalin as an alternative 1