Starting dose of gabapentin for patients with post-herpetic neuralgia--a dose-response study

Gabapentin has been shown to provide pain relief for post-herpetic neuralgia at dosage of 1200 to 2400 mg/day. However, the initial dosing strategy has not been thoroughly investigated. The purpose of this study was to establish the initial dosing strategy in the treatment of the gabapentin-naive patients with post-herpetic neuralgia.

This clinical study was an open-label, randomized, time-sequence and controlled trial. Each gabapentin-naive subject was allocated to receive either 200 mg (100 mg, twice daily), 400 mg (100 mg, four times daily), or 600 mg (200 mg, three times daily) of gabapentin for three days. The analgesic effect and occurrence of dizziness, drowsiness, and fatigue were assessed at day 0 and day 3.

A total of 61 subjects (32 male/29 female) were enrolled in this study. The intensity of pain was greatly improved in all three groups after three days of treatment (visual analog scale decreased from 6.5 +/- 1.6 to 4.5 +/- 2.1, P < 0.05). There was no statistically significant difference among subjects taking 200 mg, 400 mg, or 600 mg with respect to dizziness, drowsiness or fatigue.

This study shows that elderly gabapentin-naive subjects no matter whether receiving 200, 400 or 600 mg/day of gabapentin benefited a moderate pain relief with minimal side effects at the first three days of treatment. Since starting with a minimal dose of 200 mg/day did not offer a better reduction of side effects, we suggest that 600 mg/day gabapentin could be a safe and effective starting dose for patients with post-herpetic neuralgia.