Following is the abstract of the above paper (Stumman, et al., 2005) as well as the last paragraph from the discussion section:

Abstract:
Tetrodotoxin-resistant and tetrodotoxin-sensitive Na+ channels contribute to the abnormal spontaneous firing in dorsal root ganglion neurons associated with neuropathic pain. Effects of the anti-nociceptive agent ralfinamide on tetrodotoxin-resistant and tetrodotoxin-sensitive currents in rat dorsal root ganglion neurons were therefore investigated by patch clamp experiments. Ralfinamide inhibition was voltage-dependent showing highest potency towards inactivated channels. IC50 values for tonic block of half-maximal inactivated tetrodotoxin-resistant and tetrodotoxin-sensitive currents were 10 _M and 22 _M. Carbamazepine, an anticonvulsant used in the treatment of pain, showed significantly lower potency. Ralfinamide produced a hyperpolarising shift in the steady-state inactivation curves of both currents confirming the preferential interaction with inactivated channels. Additionally, ralfinamide use and frequency dependently inhibited both currents and significantly delayed repriming from inactivation. All effects were more pronounced for tetrodotoxin-resistant than tetrodotoxin-sensitive currents. The potency and mechanisms of actions of ralfinamide provide a hypothesis for the anti-nociceptive properties found in animal models.

From Discussion:
The overall conclusion is that the voltage-dependent inhibitory properties of ralfinamide against tetrodotoxin-resistant and tetrodotoxin-sensitive currents in dorsal root ganglion neurons provide a hypothesis to explain the anti-neuropathic properties demonstrated in animal models. The stronger anti-hyperalgesic and anti-allodynic effects in animal models of ralfinamide as compared to carbamazepine may arise from the ability of ralfinamide in clinical relevant doses to strongly attenuate both tetrodotoxin-resistant and tetrodotoxin-sensitive currents in dorsal root ganglion neurons, while clinical doses of carbamazepine may mainly influence tetrodotoxin-sensitive currents. The tetrodotoxin-sensitive and especially the tetrodotoxin-resistant blocking properties of ralfinamide are further increased when the currents are subjected to high frequency repetitive activation, as in hyperexcitability conditions.