Gabapentin for Postherpetic Neuralgia
Yes, gabapentin is highly effective for treating postherpetic neuralgia (PHN) and is recommended as a first-line oral pharmacological treatment. 1, 2
Evidence for Efficacy
Gabapentin demonstrates robust efficacy for established PHN based on FDA-approved clinical trials and guideline recommendations:
The American College of Physicians recommends gabapentin as first-line oral therapy for PHN, with proven efficacy across the dose range of 1800-3600 mg/day, though no additional benefit is shown above 1800 mg/day. 1
FDA-approved trials in 563 patients with PHN lasting more than 3 months after rash healing showed statistically significant pain reduction compared to placebo, with benefits appearing by week 1 and maintained throughout treatment. 2
A landmark JAMA trial demonstrated pain scores decreased from 6.3 to 4.2 points on an 11-point scale with gabapentin versus 6.5 to 6.0 with placebo (P<0.001), with additional improvements in sleep interference, mood, and quality of life. 3
Recommended Dosing Protocol
The evidence-based titration schedule for PHN is:
Start with 300 mg on day 1, increase to 600 mg on day 2 (divided doses), then 900 mg on day 3 (divided doses). 1
Titrate upward in 600-1200 mg/day increments at 3-7 day intervals to reach the target dose of 1800-3600 mg/day in three divided doses. 2
The typical effective adult regimen is 2400 mg/day in divided doses, though doses up to 3600 mg/day may be used. 4
For elderly patients, start with lower initial doses and titrate more slowly to minimize side effects. 1
Important Caveats
Gabapentin is NOT effective for preventing PHN when given during acute herpes zoster—it only treats established PHN:
A 2019 double-blind RCT found no benefit of gabapentin started within 72 hours of rash onset for preventing PHN at 12 weeks (18.2% vs 9.5% with placebo, p=0.144), with patients actually reporting worse quality of life. 5
A 2016 prospective controlled study similarly showed low-dose gabapentin during acute herpes zoster was not effective in preventing PHN (6.1% vs 3.8%, p=0.67). 6
Side Effects and Monitoring
Common adverse effects that require monitoring include:
Somnolence occurs in approximately 80% of patients receiving gabapentin, which may actually improve sleep scores in PHN patients. 4
Dizziness, ataxia, peripheral edema, and infection are more frequent with gabapentin, though withdrawal rates are comparable to placebo (13.3% vs 9.5%). 3
Mental clouding and sedation are particularly concerning in elderly patients, requiring careful dose titration. 1
Alternative and Adjunctive Options
If gabapentin provides inadequate response:
Consider pregabalin (150-600 mg/day in two divided doses) as a second-line gabapentinoid with NNT of 4.93. 1
Tricyclic antidepressants, particularly nortriptyline, have superior efficacy (NNT=2.64) and may be preferred over amitriptyline due to better tolerability. 1, 7
Topical lidocaine patches provide excellent efficacy (NNT=2) with minimal systemic absorption, making them ideal for elderly patients or those with localized pain. 1
Capsaicin 8% patches can provide relief for at least 12 weeks after a single 30-minute application. 4, 1
Combination therapy (e.g., morphine with gabapentin) may allow lower doses of each medication when single agents fail. 1