The addition of gabapentin to valacyclovir within 72 hours of onset of a herpes zoster rash was not found to provide further relief from acute herpetic pain or to better prevent postherpetic neuralgia (PHN), according to a study published in PLoS One.
Patients 50 years or older with herpes zoster were enrolled from 17 primary care centers in Spain within 72 hours of rash onset. Study participants had moderate to severe pain (ie, a score ≥4 on a 10-point visual analog scale [VAS]) and were randomly assigned to receive gabapentin (n=49) or placebo (n=48) for a period of 5 weeks. All patients were administered valacyclovir for 7 days, and received analgesia as needed. The starting dose of gabapentin was 300 mg/d and titrated to up to 1800 mg/d. Study participants were followed for 7 weeks, and pain intensity evaluated at 12 weeks was the study’s primary outcome.
At 12 weeks, pain was reported by 18.2% of patients who received gabapentin and by 9.5% of individuals who received placebo (odds ratio, 2.59; 95% CI, 0.59-11.28; P =.144). At 12 weeks, a VAS pain score ≥4 was reported by 12.1% and 0% of patients administered gabapentin and placebo, respectively. The incidence of neuropathic pain at the 12-week follow-up was comparable in patients administered gabapentin and placebo (12.5% vs 10.8%, respectively). Of 33 patients who received gabapentin, 30 reported ≥50% reduction in pain at 12 weeks vs 100% in the placebo group (P =.046).
Compared with placebo, treatment with gabapentin was associated with worse health-related quality of life (Summary Scale Mental on Short-Form-12: 42.6±6.5 vs 38.1±9.0, respectively; P =.018; Role Emotional on Short-Form-12: 21.8±2.6 vs 18.7±5.2, respectively; P =.001) and poorer sleep quality (sleep disturbance on Medical Outcomes Study-Sleep questionnaire: 22.8±26.6 vs 32.7±21.7, respectively; P =.028; sleep adequacy on Medical Outcomes Study-Sleep questionnaire: 78.7±26.2 vs 70.3±26.2, respectively; P =.005).
Study limitations include a small sample size, the recruitment of patients from predominantly primary health care centers, and a short follow-up period.
“Clinicians must be aware of the side effects of gabapentin, such as dizziness, sedation, worsening of cognitive impairment, and ataxia, and the growing evidence that some patients may abuse [or] misuse gabapentin due to its euphoric effects,” noted the study authors.
Bulilete O, Leiva A, Rullán M, et al. Efficacy of gabapentin for the prevention of postherpetic neuralgia in patients with acute herpes zoster: a double blind, randomized controlled trial. PLoS One. 2019;14(6):e0217335.