Objective
To evaluate the effects of gabapentin and clonidine on neuropathic pain in an experimental pain model.

Method
24 male adult rats were anesthetized and the sciatic nerve was exposed. Each exposed nerve was electrically injured with 10 volts for 10 seconds by two needle electrodes. Rats were divided into three groups by treating with gabapentin, clonidine and sham. Gabapentin and clonidine were given orally from post operation day 3 to 7 in gabapentin and clonidine groups respectively. To evaluate the presence of mechanical allodynia, withdrawal frequency was tested by Von Frey hair in the same days. After post operation day 7, all the medications were discontinued and mechanical allodynia was evaluated at post operation day 14.

Result: Neuropathic pain was developed after electrical injury in all the rats. Withdrawal frequency is more decreased in gabapentin and clonidine groups than sham group in post operation day 4 to 7. The withdrawal frequency was 2.88⁑0.83, 2.75⁑0.89, 3.13⁑0.99, 3.25⁑1.28 in gabapentin group and 3.38⁑0.92, 4.50⁑2.20, 3.25⁑1.17, 3.50⁑0.93 in clonidine group in post operation day 4, 5, 6, 7, respectively. In post operation day 14, withdrawal frequency was increased and showed no difference compared to the sham group.

Conclusion
Gabapentin and clonidine can suppress the neuropathic pain in an experimental pain model. There was no different effect on the neuropathic pain suppression between gabapentin and clonidine.