Abstract

Background

Antiepileptic drugs have been used in pain management since the 1960s; some have shown efficacy in treating different neuropathic pain conditions. Phenytoin is an established antiepileptic drug that has been used occasionally to treat intractable trigeminal neuralgia.

Objectives

To assess the analgesic efficacy and adverse effects of the antiepileptic drug phenytoin in neuropathic pain and fibromyalgia.

Search methods

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 2), MEDLINE, and EMBASE to 28 February 2012, together with reference lists of retrieved papers and reviews, and ClinicalTrials.gov.

Selection criteria

We planned to include randomised, double‐blind studies of eight weeks duration or longer, comparing phenytoin with placebo or another active treatment in chronic neuropathic pain or fibromyalgia.

Data collection and analysis

Two review authors would independently extract data for efficacy and adverse events, and examine issues of study quality.

Main results

We did not identify any studies that satisfied the inclusion criteria.

Authors' conclusions

This review uncovered no evidence of sufficient quality to support the use of phenytoin in chronic neuropathic pain or fibromyalgia.

Author(s)

Fraser Birse, Sheena Derry, R Andrew Moore

Abstract

Plain language summary

Phenytoin for neuropathic pain and fibromyalgia in adults

Nerves which have been damaged by injury or disease can continue to produce pain. This type of pain is called neuropathic pain. Some antiepileptic medications can help neuropathic pain. Phenytoin is an antiepileptic medication, and the aim of this review was to assess how effective phenytoin is for neuropathic pain and fibromyalgia. We identified no good quality studies of phenytoin used in this situation. When used to treat epilepsy, phenytoin can cause potentially troublesome adverse events, affecting nervous tissue, the blood, and unborn children. Based on current evidence, phenytoin cannot be recommended for treating neuropathic pain. Other antiepileptic drugs such as pregabalin, gabapentin, and carbamazepine have been shown to be of value in neuropathic pain.

Author(s)

Fraser Birse, Sheena Derry, R Andrew Moore

Reviewer's Conclusions

Authors' conclusions 

Implications for practice 

This review could find no evidence of sufficient quality to support the use of phenytoin in chronic neuropathic pain and fibromyalgia.

Implications for research 

If phenytoin is to be considered for use in this context, high‐quality, randomised, double‐blinded, placebo‐controlled trials need to be carried out to build a base of evidence supporting its use or confirming it to be ineffective. This seems unlikely to occur due to the cost of such studies and the lack of financial incentive behind them, in this case because phenytoin is out of patent and there would be little or no profit to justify the large trial costs.

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