Lacosamide, a new anti-epileptic, alleviates neuropathic pain-like behaviors in rat models of spinal cord or trigeminal nerve injury

The effect of systemic administration of lacosamide, a newly developed anti-epileptic, on neuropathic pain-like behaviors was examined in rats after ischemic injury to the infraorbital nerve or spinal cord using a photochemical method. In rats with infraorbital nerve injury, lacosamide reduced mechanical hypersensitivity and the effect was markedly stronger in female than in male rats. In spinal cord injured female rats 10-20 mg/kg lacosamide dose-dependently alleviated the mechanical and cold allodynia-like behaviors without causing motor impairments or marked sedation. Administration of lacosamide twice daily at 20 mg/kg for 7 days totally alleviated the allodynia-like state in spinally-injured rats with no tolerance. Following treatment cessation the cold and the static allodynia reappeared but the effect on dynamic mechanical allodynia (brushing) was maintained until day 11. Lacosamide also produced hypothermia at antinociceptive doses in rats. It is suggested that this novel compound may be useful as an analgesic for treating central and trigeminal neuropathic pain. Furthermore, there may be a gender difference to the effect of lacosamide with female rats being more responsive to the treatments. (c) 2006 Elsevier B.V. All rights reserved.