How Effective Is Carbamazepine For Neuropathy Pain?

Today's post from onlinelibrary.wiley.com (see link below) is an objective assessment of the effects of carbamazepine on neuropathic pain and as such is always useful for neuropathy patients looking for confirmation that what they're being prescribed is what the doctor says it is. Carbamazepine has become increasingly popular recently, as an alternative to other anti-epilepsy drugs such as Lyrica, which has a possibly deserved bad press. However, does the research show that it works? This article suggests that it does...for some people but with caveats. Pretty much the same as all other drugs used to treat neuropathic pain then! Worth a read if you're on Carbamazepine, or likely to encounter it in the course of your treatment options.

Carbamazepine for chronic neuropathic pain and fibromyalgia in adults 
Philip J Wiffen1,*, Sheena Derry1, R Andrew Moore1,Eija A Kalso2,3
Editorial Group: Cochrane Pain, Palliative and Supportive Care Group
Published Online: 10 APR 2014
Assessed as up-to-date: 7 FEB 2014

DOI: 10.1002/14651858.CD005451.pub3

Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
The Cochrane Library
Read a clinical summary of this review on

Abstract

Background

This is an update of a Cochrane review entitled 'Carbamazepine for acute and chronic pain in adults' published in Issue 1, 2011. Some antiepileptic medicines have a place in the treatment of neuropathic pain (pain due to nerve damage). This updated review considers the treatment of chronic neuropathic pain and fibromyalgia only, and adds no new studies. The update uses higher standards of evidence than the earlier review, which results in the exclusion of five studies that were previously included.

Objectives

To assess the analgesic efficacy of carbamazepine in the treatment of chronic neuropathic pain and fibromyalgia, and to evaluate adverse events reported in the studies.

Search methods

We searched for relevant studies in MEDLINE, EMBASE and CENTRAL up to February 2014. Additional studies were sought from clinical trials databases, and the reference list of retrieved articles and reviews.

Selection criteria

Randomised, double blind, active or placebo controlled trials (RCTs) investigating the use of carbamazepine (any dose, by any route, and for at least two weeks' duration) for the treatment of chronic neuropathic pain or fibromyalgia, with at least 10 participants per treatment group. Participants were adults aged 18 and over.

Data collection and analysis

Two study authors independently extracted data on efficacy, adverse events, and withdrawals, and examined issues of study quality. Numbers needed to treat for an additional beneficial effect (NNT) or harmful effect (NNH) with 95% confidence intervals (CIs) were calculated from dichotomous data.

We performed analysis using three tiers of evidence. First tier evidence derived from data meeting current best standards and subject to minimal risk of bias (outcome equivalent to substantial pain intensity reduction, intention-to-treat analysis without imputation for dropouts, at least 200 participants in the comparison, at least 8 weeks' duration, parallel design), second tier from data that failed to meet one or more of these criteria and were considered at some risk of bias but with adequate numbers in the comparison, and third tier from data involving small numbers of participants that was considered very likely to be biased or used outcomes of limited clinical utility, or both.

Main results

Ten included studies (11 publications) enrolled 480 participants with trigeminal neuralgia, diabetic neuropathy, and post stroke pain. Nine studies used a cross-over design, and one a parallel group design. Most of the studies were of short duration, lasting four weeks or less.

No study provided first or second tier evidence for an efficacy outcome. Using third tier evidence, carbamazepine generally provided better pain relief than placebo in the three conditions studied, with some indication of pain improvement over mainly the short term, but with poorly defined outcomes, incomplete reporting, and in small numbers of participants. There were too few data in studies comparing carbamazepine with active comparators to draw any conclusions.

In four studies 65% (113/173) of participants experienced at least one adverse event with carbamazepine, and 27% (47/173) with placebo; for every five participants treated, two experienced an adverse event who would not have done so with placebo. In eight studies 3% (8/268) of participants withdrew due to adverse events with carbamazepine, and none (0/255) with placebo. Serious adverse events were not reported consistently; rashes were associated with carbamazepine. Four deaths occurred in patients on carbamazepine, with no obvious drug association.

Authors' conclusions

Carbamazepine is probably effective in some people with chronic neuropathic pain, but with caveats. No trial was longer than four weeks, had good reporting quality, nor used outcomes equivalent to substantial clinical benefit. In these circumstances, caution is needed in interpretation, and meaningful comparison with other interventions is not possible.

Plain language summary

Carbamazepine for chronic neuropathic pain and fibromyalgia in adults

Neuropathic pain is pain coming from damaged nerves. It is different from pain messages carried along healthy nerves from damaged tissue (a fall, or cut, or arthritic knee). Neuropathic pain is treated by different medicines than pain from damaged tissue. Medicines like paracetamol or ibuprofen are not effective in neuropathic pain, while medicines that are sometimes used to treat depression or epilepsy can be very effective in some people. Our understanding of fibromyalgia (a condition of persistent, widespread pain and tenderness, sleep problems, and fatigue) is lacking, but fibromyalgia can respond to the same medicines as neuropathic pain.

Carbamazepine was developed to treat epilepsy, but it is now used to treat various forms of chronic pain. We performed searches (up to February 2014) to look for clinical trials where carbamazepine was used to treat neuropathic pain or fibromyalgia. We found 10 studies involving 418 people involved in testing carbamazepine. Studies were not generally of very good quality. Most were very small, as well as of short duration. Studies lasting only one or two weeks are unhelpful when pain can last for years.

There was not enough good quality evidence to say how well carbamazepine worked in any neuropathic pain condition. Pooling four small studies showed that it was better than placebo, but the result cannot be relied upon. There was not enough information from these studies to make any reliable comment on adverse events or harm.

Carbamazepine is probably helpful for some people with chronic neuropathic pain. It is not possible to know beforehand who will benefit and who will not. 


http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD005451.pub3/abstract