This study was aimed at characterizing the anticonvulsant effects of levetiracetam in combination with gabapentin, in the mouse 6 Hz psychomotor seizure model. Herein, psychomotor seizures were evoked in male albino Swiss mice by a current (32 mA, 6 Hz, 3 s stimulus duration) delivered via ocular electrodes. Type II isobolographic analysis was used to characterize the anticonvulsant interactions between the drugs in combination, for fixed-ratios of 1:1, 1:2, 1:5 and 1:10. The type II isobolographic analysis revealed that the combinations of levetiracetam with gabapentin for the fixed-ratios of 1:5 and 1:10 were supra-additive (synergistic; P<0.05) in terms of seizure suppression, while the combinations for the fixed-ratios of 1:1 and 1:2 were additive in the mouse 6 Hz psychomotor seizure model. We conclude that, as the combinations of levetiracetam with gabapentin for the fixed-ratios of 1:5 and 1:10 exerted supra-additive (synergistic) interaction in the mouse 6 Hz psychomotor seizure model, this may be considered as particularly favorable combinations in further clinical practice.
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