THE EFFECT OF NOVEL ANTIEPILEPTIC DRUGS IN RAT EXPERIMENTAL-MODELS OFACUTE AND CHRONIC PAIN

The novel anti-epileptic drugs lamotrigine, felbamate and gabapentin w ere compared in rat experimental models of acute (tail flick) and chro nic pain: the chronic constriction injury and spinal nerve ligation mo dels. Lamotrigine (10-100 mg/kg, s.c.), felbamate (150-600 mg/kg, i.p. ) and gabapentin (30-300 mg/kg, i.p.) each reversed cold allodynia (ch ronic constriction injury model) with ED50 values of 28, 241 and 103 m g/kg, respectively, 1 h post-dose. However, only gabapentin reversed t actile allodynia (spinal nerve ligation model) with an ED50 of 34 mg/k g (i.p.). The established anti-epileptic drugs, carbamazepine (1-30 mg /kg, i.p.) and phenytoin (1-100 mg/kg, s.c.), were ineffective in both models. The anti-allodynic effect of the newer anti-epileptic drugs w as observed at doses that were either ineffective or produced only a n egligible effect on acute nociceptive function and/or locomotor activi ty. In conclusion, the data suggest that the newer anti-epileptic drug s appear to have the potential to be effective alternatives to either carbamazepine or phenytoin in the treatment of neuropathic pain. Howev er, only gabapentin ameliorated both cold and touch hyperesthesias. (C ) 1997 Elsevier Science B.V.