Efficacy of pregabalin and gabapentin for neuropathic pain in spinal-cord injury: an evidence-based evaluation of the literature.

backgroundSpinal-cord injury (SCI) is a leading cause of neuropathic pain (NP). Current pharmaceutical treatments for NP in SCI patients are not effective. Two promising options are gabapentin (GP) and pregabalin (PB). Their predominant mechanism of action is believed to be the inhibition of calcium currents, leading in turn to reduced neurotransmitter release and attenuation of postsynaptic excitability. This could explain much of their efficacy in the treatment of both seizure disorders and pain syndromes. However, evidence for their efficacy in attenuating NP of SCI is still controversial.

objectiveTo efficiently integrate valid information and provide a basis for rational decision making, through determining PB and GP efficacy in treating NP in SCI.

methodsLiterature was systematically reviewed. Medline, Embase, CINAHL and Cochrane Database were searched using search terms 'gabapentin', 'pregabalin', 'neurontin', 'lyrica', 'neuropathic pain' and 'spinal-cord injury'. Studies were assessed independently by two authors.

resultsFive studies were eligible for inclusion. Two of them studied PB and three GP. Both GP and PB appear to be efficacious for NP in SCI. A clear comparison between the two drugs could not be performed. The literature data suggest that PB is more efficacious than GP in many important variables for NP in SCI, although PB use is followed by more side effects than GP. PB reduced Visual Analogue Score (VAS) in both studies (P < 0.001 and P = 0.016). On the other hand, for GP a maximum dosage of 3,600 mg/day reduced VAS score (P = 0.000), whereas a maximum dosage of 1,200 mg/day failed to do so.

conclusionThere is a lack of studies comparing GP and PB in treating NP in SCI. This systematic review indicates the possible efficacy of PB and GP in NP of SCI. Recommendations for future research to inform clinical practice should include cost-effectiveness studies and dose-response analysis in order to determine the schema employed and the duration of treatment.