Inhibitory effects of levetiracetam on absence seizures in a novel absence-like epilepsy animal model, Groggy rat.

Levetiracetam (LEV) is known to inhibit convulsive seizures and is clinically used for treating both partial and generalized seizures. The study was performed to determine whether LEV possesses an inhibitory effect on absence seizures in a novel genetic animal model of absence epilepsy, Groggy (GRY) rats. Single injections of LEV at doses ranging from 20 to 160 mg/kg i.p. markedly inhibited absence seizures in GRY rats. The anti-absence action of LEV was potent and the cumulative duration of spike and wave discharges (SWD) in GRY rats was almost completely suppressed even at 20 mg/kg (i.p.). When the time-course of the inhibitory action of LEV (80 mg/kg i.p.) was examined up to 24 h after the treatment, the appearance of SWD was suppressed for over 6 h after injection of LEV in contrast to the action of sodium valproate (200 mg/kg i.p.) which had a very short effect (< 2 h). The maximum level of blood concentration of LEV was attained within 2 h after administration, and the drug disappeared from the blood in 24 h with T(¹/₂) of 2.7 h. These results revealed that LEV displays potent and relatively long-lasting inhibitory effects on absence seizures in GRY rats.