The antihyperalgesic effects of gabapentinoids, carbamazepine and its keto analogue, oxcarbazepine, in capsaicin-induced thermal hyperalgesia

Abstract

It is aimed to investigate and compare the antihyperalgesic effects of 100 mg/kg (p.o.) gabapentin, 30 mg/kg (p.o.) pregabalin, 30 mg/kg (p.o.) carbamazepine and 120 mg/kg (p.o.) oxcarbazepine in a time-dependent manner at a 1-60 minute time-interval, in capsaicine-evoked thermal hyperalgesia model of rats via Hargreave’s method. Thermal thresholds were significantly increased by 100 mg/kg gabapentin, 30 mg/kg pregabalin and 30 mg/kg carbamazepine treatment at 15-30-45, 15-30-45-60and 15-30-45 minute time-points, respectively, after capsaicin injection compared to capsaicin-treated group while 120 mg/kg oxcarbazepine was ineffective at any time points. It is suggested that gabapentin, pregabalin and carbamazepine are effective in inflammatory pain and capsaicin receptor, TRPV1 channels, may contribute to antihyperalgesic effects since these antiepileptics reversed thermal hyperalgesia induced by capsaicin.