Phenytoin for neuropathic pain and fibromyalgia in adults

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.