Gabapentin for Adults with Neuropathic Pain A Review of the Clinical Evidence and Guidelines
Gabapentin is an anticonvulsant drug that has been used for a number of off-label indications, including neuropathic pain. It is thought to act by binding to calcium channels and modulating calcium influx, or by blocking new synapse formation. Neuropathic pain tends to be chronic, is complex, and can be difficult to treat effectively. Treatment often involves pharmacologic and physical therapies, although conventional analgesics may not be effective. Gabapentin, and the structurally related pregabalin (i.e., gabapentinoids), have been reported to possess potential for misuse, with anecdotal reports of black market sales and trading within prisons. In high doses, gabapentinoids may be associated with sedative and dissociative or psychedelic effects. In 2012, CADTH conducted a Rapid Review on the abuse and misuse potential of pregabalin. This review identified two crossover randomized controlled trials (RCTs), one database analysis, one analysis of anecdotal online reports and three case reports related to the misuse or abuse of pregabalin. In healthy volunteers, the combination of pregabalin and oxycodone was associated with effects such as having pleasantunpleasant bodily sensations and coasting (feeling spaced out), while each drug alone did not alter subjective effects. Pregabalin was associated with more ‘drug-taking behavior’ (e.g., good drug effect and high) than diazepam among RCT participants with a history of drug and alcohol abuse. A review of a Swedish database identified 16 reports of pregabalin abuse and no gabapentin reports, out of 198 reports indicative of abuse or addition to any drug between 1980 and 2009. Reports of recreational misuse of pregabalin and gabapentin were also found in a review of anecdotal online data. This Rapid Review concluded that there is limited evidence regarding the abuse and misuse of pregabalin but existing data suggests that certain populations with a history of substance abuse may be at increased risk to abuse pregabalin. The purpose of this report is to review the clinical evidence on the efficacy, safety and guidelines for use of gabapentin in adults with neuropathic pain, and to examine evidence on the misuse or abuse of gabapentin and other drugs for neuropathic pain.