RESUMO
BACKGROUND: Levetiracetam (LEV) is a novel anticonvulsant with proven antinociceptive properties. However, the antinociceptive and pronociceptive effect of this drug has not yet been fully elucidated in a tonic pain model. METHODS: Thirty-six male rats (Wistar) were randomized into six groups and underwent the formalin test as follows: rats in the control group were administered 50µL of 1% formalin in the paw; sham-group rats were administered 50µL of saline in the paw to mimick the application of formalin; the four experimental groups were administered LEV intragastrically (ig) (50, 100, 200 and 300mg/kg), and 40min later 50µL of 1% formalin was injected in the paw. RESULTS: LEV exhibited antinociceptive effect in the 300mg/kg LEV group (p<0.05) and a pronociceptive effect in the 100mg/kg LEV group (p<0.05) and in the 50mg/kg LEV group (p<0.001). CONCLUSIONS: The antinociceptive and pronociceptive effect of LEV in a tonic pain model is dose-dependent.