Gabapentin add-on for drug-resistant partial epilepsy

Marson AG, Kadir ZZ, Hutton JL, Chadwick DW

Published Online:

October 7, 2009

Gabapentin is effective as a short-term add-on treatment for partial epilepsy.

Epilepsy is a disorder where recurrent seizures are caused by abnormal electrical discharges from the brain. The review of trials found that a new antiepileptic drug, gabapentin is effective in the short-term when used with other drugs by people with drug-resistant partial epilepsy. The most common adverse effects caused by gabapentin are ataxia (poor coordination and unsteady gait), dizziness, fatigue, nausea, drowsiness and headaches. Research is needed into the effects of the long-term use of gabapentin.

Abstract (click to read)

Background:

The majority of people with epilepsy have a good prognosis and their seizures are well controlled by a single antiepileptic drug, but up to 30% develop refractory epilepsy, especially those with partial seizures. In this review we summarize the current evidence regarding a new antiepileptic drug, gabapentin, when used as an add-on treatment for drug-resistant partial epilepsy

Objectives:

To evaluate the efficacy and tolerability of gabapentin when used as an add-on treatment for people with drug-resistant partial epilepsy.

Search strategy:

We searched the Cochrane Epilepsy Group's Specialized Register (July 2007), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 2, 2007), and MEDLINE (1966 to July 2007). No language restrictions were imposed. We also contacted the manufacturers of gabapentin and researchers in the field to seek any ongoing or unpublished studies.

Selection criteria:

Randomized placebo controlled double blind add-on trials of gabapentin in people with drug-resistant partial epilepsy.

Data collection and analysis:

Two review authors independently selected trials for inclusion and extracted the relevant data. The following outcomes were assessed: (a) 50% or greater reduction in seizure frequency; (b) treatment withdrawal (any reason); (c) adverse effects. Primary analyses were intention-to-treat. Sensitivity best and worst case analyses were also undertaken. Summary odds ratios were estimated for each outcome. Dose response was evaluated in regression models, and Number Needed to Treat (NNT) was calculated for individual doses.

Main results:

Five trials were included representing 997 randomized participants.
Overall odds ratio (OR) with 95% confidence intervals (CIs) for 50% or greater reduction in seizure frequency compared to placebo was 1.93 (95% CI 1.37 to 2.71). Dose regression analysis shows increasing efficacy with increasing dose, with 28.5% (21.5 to 36.7) of people responding to 1800 mg of gabapentin compared to placebo, NNT 6.7 (3.0 to 10.5).
Treatment withdrawal OR (95% CI) compared to placebo was 1.05 (95% CI 0.68 to 1.61).
Adverse effects with OR (99% CI) compared to placebo: dizziness 2.22 (99% CI 1.28 to 3.85); fatigue 2.28 (99% CI 1.15 to 4.52) and somnolence 2.01 (99% CI 1.24 to 3.28) were significanty associated with gabapentin.

Authors' conclusions:

Gabapentin has efficacy as an add-on treatment in people with drug-resistant partial epilepsy. However, trials reviewed were of relatively short duration, and provide no evidence for the long-term efficacy of gabapentin. Results cannot be extrapolated to monotherapy or people with other epilepsy types.

This record should be cited as:

Marson AG, Kadir ZZ, Hutton JL, Chadwick DW. Gabapentin add-on for drug-resistant partial epilepsy. Cochrane Database of Systematic Reviews 2000, Issue 3. Art. No.: CD001415. DOI: 10.1002/14651858.CD001415

Assessed as up to date:

July 1, 2007

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Primary Review Group:

Epilepsy Group

Health topics:

Neurology > Epilepsy > Drugs for broad populations

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Gabapentin add-on for drug-resistant partial epilepsy

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