effect of five common anticonvulsant drugs on naloxone-precipitated morphine withdrawal in mice

this study was designed to assess the effect of five common anticonvulsant drugs on naloxone-precipitated withdrawal syndrome in morphine-dependent mice. male mice (25-35 g) were made dependent by increasing doses of morphine (30-90 mg/kg). at least three doses of phenytoin, carbamazepine, sodium valproate, lamotrigine and topiramate were injected i.p. to morphine-dependent mice 45 min prior to induction of withdrawal syndrome by naloxone (5 mg/kg, i.p.). control animals received vehicle. number of jumpings was counted and ptosis, tremor, piloerection and diarrhea were checked in a 30 min period started just after naloxone injection. results showed that lamotrigine, phenytoin and sodium valproate were ineffective in suppression of withdrawal syndrome while carbamazepine produced a dose-dependent reduction of jumpings. topiramate at the maxium applied dose (100 mg/kg) significantly reduced number of naloxone-elicited jumpings. it seems that carbamazepine by inhibition of n-methyl-d-aspartate (nmda) receptors and topiramate by inhibiting kainite-activated (ampa) receptor antagonists suppress morphine withdrawal syndrome but further studies are needed to have a definite conclusion.