Flecainide for the treatment of chronic neuropathic pain: a Phase II trial

Background : Management of neuropathic pain is challenging. Medications that interfere with sodium channel transport, such as lidocaine, mexilitene and flecainide, are promising as analgesics. Objective : In a general population of patients with a working diagnosis of neuropathic pain, whether if flecainide produces enough of an improvement in pain to warrant further clinical study is determined. Design : Phase I/II prospective exploratory clinical trial. Eligible patients were observed for week 1, then 50 mg flecainide was administered twice daily for week 2 and then administered 100 mg twice daily for week 3. Setting/ Subjects : Multi-institutional members of the Eastern Co-operative Oncology Group. Patients had neuropathic pain diagnosed by their oncologists as defined by the International Association for the Study of Pain and a diagnosis of cancer or AIDS. Measurements : The Wisconsin Brief Pain Inventory was used. The primary endpoint was a decrease of 3 points (0—10 numerical scale) or a decrease of 50% in the worst pain rating at either day 15 or day 22 relative to the average of days 1 and 8 ratings. Results : Nineteen patients were registered for the study. Four patients were ineligible. Of the remaining 15, one was unevaluable due to incomplete pain rating. Four out of 14 patients had an average drop of 5 points or 53% in their worst pain ratings on a 0—10 numerical scale of pain. No patients withdrew from study because of toxicity. There were no life-threatening or lethal toxicities. All patients were alive at the time of the analysis. Conclusions : Flecainide produced a 30% response rate. Response in this study was defined to be highly relevant and clinically significant reduction in pain. The drug merits study in a randomized placebo-controlled trial. Palliative Medicine 2007; 21 : 667—672