mexiletine useful for treating neuropathic pain in peripheral neuropathy ,study

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J Orthop Sci. 2005;10(3):315-20.

Effect of sodium channel blocker (mexiletine) on pathological ectopic

firing pattern in a rat chronic constriction nerve injury model.

Nakamura S, Atsuta Y.

Department of Orthopedic Surgery, Asahikawa Medical College, 2-1-1-1

Midorigaoka-Higashi, Asahikawa, 078-8510, Japan.

We studied the efficacy of mexiletine as a sodium channel blocker for

neuropathic pain by investigating the effect of mexiletine on the

pathological ectopic firing pattern in a chronic constriction nerve

injury (CCI) model. The experiment was conducted with 60 male Wistar

rats. The CCI model was created by loosely ligating the sciatic

nerve. After breeding 7 days, the frequency and pattern of ectopic

firing antidromically recorded from the sural nerve and the amplitude

of antidromic sensory nerve-evoked potential were analyzed.

The CCI rats were given an intravenous injection of normal saline and

mexiletine (5 or 15 mg/kg). Mexiletine significantly suppressed

spontaneous firing frequency, an on-off firing pattern that consisted

of cyclic bursting spikes and ectopic firing generation under the

hypoxic condition. Mexiletine did not influence the amplitude of A-

delta component in the antidromic sensory nerve-evoked potential.

Mexiletine suppressed ectopic firing by blocking activity of the

abnormal sodium channel at the nerve-injured site and dorsal root

ganglion without blocking nerve conduction.

This study suggests that mexiletine is useful for treating

neuropathic pain in peripheral neuropathy.