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.

Authors' conclusions: 

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

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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 strategy: 

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.

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