Gabapentin Dosing for Postherpetic Neuralgia

Initial Titration and Maintenance Dose

The Mayo Clinic guidelines recommend initiating gabapentin at 100-300 mg at bedtime or 100-300 mg three times daily, with increases of 100-300 mg every 1-7 days as tolerated, up to a maximum of 3600 mg/day in three divided doses, with an adequate trial requiring 3-8 weeks for titration plus 2 weeks at maximum dose 1, 2
The evidence shows that gabapentin at up to 3600 mg/day significantly decreased pain compared to placebo in a randomized trial of 563 PHN patients, with a number needed to treat (NNT) of 4.39 5, 6, 7

Administer gabapentin three times daily with a maximum interval of 12 hours between doses, due to its nonlinear pharmacokinetics from saturable absorption via the L-amino acid transport system in the proximal small intestine 1, 2
Dose adjustment is mandatory in patients with renal dysfunction, with recommended doses ranging from 100-300 mg/day as a single daily dose for CrCl <15 mL/min to 900-3600 mg/day in three divided doses for CrCl ≥60 mL/min 1, 2

Gabapentin 900 mg resulted in 66% decreased pain and allodynia compared to 33% with placebo, demonstrating its efficacy in pain management 3, 4
Side effects, such as dizziness, somnolence, dry mouth, and constipation, are dose-dependent and can be minimized by starting low and titrating slowly, with approximately 80% of patients reporting somnolence 3, 4, 8