ABSTRACT
BACKGROUND: Anticonvulsants and antidepressants are adjuvant analgesic drugs that are used widely for treating chronic neuropathic pain syndromes. The combined analgesic effect of gabapentin and milnacipran was investigated with a rat neuropathic pain model. METHODS: The rat neuropathic pain model was made by ligating the spinal nerves (L5 and L6). An intrathecal catheter was inserted into the subarachnoid space. Tactile allodynia was tested with the up-down method using von Frey hair. We determined the antiallodynic effect of intraperitoneal (I.P.) and intrathecal (I.T.) gabapentin. The combined effect of I.P. gabapentin (50 mg/kg) and milnacipran (0, 10 and 30 mg/kg) was investigated. RESULTS: Intraperitoneal and intrathecal administration of gabapentin increased the threshold for tactile allodynia (the ED50 was 60.6 mg/kg and 45.5microng, respectively). Co-administration of I.P. milnacipran increased the antiallodynic effect of I.P. gabapentin in a dose-dependent fashion. CONCLUSION: The combined administration of milnacipran and gabapentin may increase the total analgesic effect during treatment of neuropathic pain.