Several lines of evidence suggest that
neuropathic pain is mediated in part by an increase in the density of voltage-sensitive
sodium channels in injured axons and the dorsal root ganglion of injured axons. The purpose of this study was to examine the safety,
analgesic efficacy, and tolerability of oral
4030W92 (a new novel
sodium channel blocker) in a group of subjects with chronic
neuropathic pain. This study used a randomized, double-blind, placebo-controlled, crossover design in 41 subjects with
neuropathic pain with a prominent
allodynia. Each subject received a 2-week course of
4030W92 (25 mg/day) and placebo separated by a 2-week washout period. At baseline, postdose day 1, day 7, and day 14, the following were measured: (1) spontaneous and evoked
pain scores, (2) dynamic and static
allodynia mapping, (3) Short Form McGill
Pain Questionnaire, and (4) blood sample for
4030W92 assay. At baseline and day 14 the following were measured: (1) thermal testing in the painful area, (2) Medical Outcomes Study Short Form 36 Questionnaire, and (3) patient global satisfaction.
Allodynia severity was significantly lower (P = .046) on treatment day 1, postdose for
4030W92 compared to placebo. However, this was not maintained on treatment day 7 or 14. The area of static
allodynia was significantly smaller (P = .03) on treatment day 7 for
4030W92 compared to placebo. However, this was not maintained to treatment day 14. There was no significant effect of
4030W92 on any other efficacy measure. Side effects were minimal.
4030W92, at 25 mg/day, produced a nonsignificant reduction in
pain without treatment limiting side effects. The maximum
analgesic effect of this
drug remains unknown.