Gabapentin shows the efficacy in preventing Postherpetic Neuralgia

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Gabapentin shows the efficacy in preventing Postherpetic Neuralgia

A recent study by M Rullán and colleagues states that gabapentin can be effective in preventing postherpetic neuralgia. The alterations of the peripheral nervous system in areas affected by the herpes zoster virus initiates chronic neuropathic pain known as post-herpetic neuralgia (PHN). The symptoms include pain, paresthesia, dysesthesia, hyperalgesia, and allodynia. No treatments are available to curb the underlying pathophysiology responsible for this disabling condition, in spite the availability of pharmacological treatments to manage these symptoms.

M Rullán et al. studies patients aged 50 years old with a pain score of 4 or higher on a visual analogue scale (VAS) suffering from herpes zoster were. A total of 134 patients were recruited from the practices of general physicians. For five weeks, the participants were randomized to receive gabapentin to a maximum of 1800 mg/day or placebo. Both arms received 1000-mg caplets of valacyclovir three times daily for 7 days (started within 72 h of the onset of symptoms) and analgesics as required. From the rash onset, the primary outcome measure was the percentage of patients with a VAS pain score of 0 at 12 weeks. The secondary outcomes measures displayed the changes in quality of life (measured by the SF-12 questionnaire), sleep disturbance (measured by the Medical Outcomes Study Sleep Scale), and percentage of patients with neuropathic pain (measured by the Douleur Neuropathique in 4 Questions).

It was thus concluded that gabapentin is an anticonvulsant type of analgesic that could hinder the onset of PHN by its anti hypersensitivity action in dorsal horn neurons.

A prospectively controlled study exhibit that low doses of gabapentin were not useful in the prevention of PHN. However, the assessment was nonrandomized, and patients were not blinded to treatment. The two main strengths of evaluation are that, as far as know, it is the first (randomized controlled trials) RCT to evaluate the effect of gabapentin on prevention of PHN, and it is an independent clinical trial funded by a public research agency. The ceiling dose of gabapentin is 1800 mg/day because it has been established that a dose higher than 1800 mg/day does not provide greater benefit; the bioavailability of gabapentin varies inversely with treatment, and high-dose regimens are related to lower patient compliance. The most recognizable side effects of gabapentin are dizziness, lethargy, and drowsiness, so their presence might compromise the blinding of patients and investigators. Although considered the use of an active placebo (a placebo that mimics the side effects of the drug underestimation), finally decided to use a “pure” placebo because of ethical concern for the patients included in the study.


Trials. 2017 Jan 14;18(1):24

Link to the source:

The original title of the article:

Efficacy of Gabapentin for Prevention of Postherpetic Neuralgia: Study Protocol for a Randomized Controlled Clinical Trial


M Rullán et al.

Therapeutic, Gabapentin, Valacyclovir, Post-herpetic Neuralgia (PHN), Neuropathic pain, Anticonvulsants, Analgesic, Prospectively controlled study, Chronic, Efficacy, Visual analogue scale (VAS), SF-12 questionnaire, Medical Outcomes Study Sleep Scale, Douleur Neuropathique, Dizziness, Lethargy, Drowsiness
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