Interactions of pregabalin with gabapentin, levetiracetam, tiagabine and vigabatrin in the mouse maximal electroshock-induced seizure model: a type II isobolographic analysis

The aim of this study was to characterize the anticonvulsant effects of pregabalin in combination with four second-generation antiepileptic drugs (i.e., gabapentin, levetiracetam, tiagabine, and vigabatrin) in the mouse maximal electroshock (MES)-induced seizure model by using the type II isobolographic analysis. Tonic hind limb extension (seizure activity) was evoked in adult male albino Swiss mice by a current (sine-wave, 25 mA, 500 V, 50 Hz, 0.2 s stimulus duration) delivered via auricular electrodes. The combination of pregabalin with gabapentin at the fixed-ratio of 1:1 was supra-additive (synergistic) in terms of seizure suppression while the combinations at the fixed-ratios of 2:1 and 4:1 were additive in the mouse MES model. Similarly, the combination of pregabalin with tiagabine at the fixed-ratio of 25:1 was supra-additive, whereas the combinations at the fixed-ratios of 100:1 and 50:1 were additive in the mouse MES model. Pregabalin with levetiracetam and vigabatrin at the fixed-ratios of 1:1, 2:1 and 4:1 were additive in this seizure model. The combinations of pregabalin with gabapentin (1:1) and pregabalin with tiagabine (25:1) appear to be favorable combinations exerting supra-additive interaction in suppressing MES-induced seizures. Pregabalin in combination with levetiracetam and vigabatrin appears to be neutral producing only additivity in the mouse MES model.