NP is complex and tends to be chronic. It develops as a result of damage to the nervous system and is characterized by when there is no stimulus or minor stimulus that causes more pain than what would be expected. Conditions such as spinal cord injury and multiple sclerosis may result in central NP, while examples of peripheral neuropathy include diabetic peripheral neuropathy and postherpetic neuralgia. NP is estimated to affect 6.9% to 10% of the general population. NP may be difficult to manage effectively and treatment often involves pharmacologic and physical therapies. Pharmacological management includes medications such as anticonvulsants, antidepressants, and serotonin-norepinephrine reuptake inhibitors. Patients generally do not respond to nonsteroidal anti-inflammatory drugs and resistance to opioid analgesics is common and thus not recommended.
Gabapentin, an anticonvulsant drug originally developed for the treatment of epilepsy, is used off-label for treating NP in Canada. Its mechanism of action is through binding to calcium channels and modulating calcium influx, resulting in antiepileptic, analgesic, and sedative effects. It is also suggested that gabapentin acts by blocking new synapse formation. Gabapentin is available in various dosages and formulations.
Gabapentin has been used off-label for the treatment of NP in Canada. Gabapentin’s efficacy and safety compared with other interventions or placebo for NP needs to be examined. There is evidence that in high doses, gabapentin may be associated with sedative and dissociative or psychedelic effects. There is also potential for misuse.
A review of the clinical evidence on the efficacy, safety, and abuse or misuse of gabapentin, as well as a review of the guidelines for the use of gabapentin in adults with NP, will help inform treatment decisions.
A limited literature search was conducted of key resources, and titles and abstracts of the retrieved publications were reviewed for the four reports addressing the effectiveness and efficacy of gabapentin for the management of NP. Full-text publications were evaluated for final article selection according to predetermined selection criteria (population, intervention, comparator, outcomes, and study designs). For the report regarding the misuse of gabapentin, a limited literature search was performed; summarized abstracts of articles potentially meeting the pre-specified inclusion criteria were reviewed.
The clinical evidence on gabapentin for NP was summarized from five reports published between 2014 and 2018. In total, the five reports reviewed 32 publications: 17 systematic reviews, three randomized controlled trials, 10 non-randomized studies, and two guidelines.
CADTH has produced four reports on the use of gabapentin for adults with NP and one report on gabapentin’s misuse.