Polygonogram for 5 antiepileptic drugs with different molecular mechanisms of actions. Levetiracetam (LEV), lacosamide (LCM), pregabalin (PGB), retigabine (RTG) and gabapentin (GBP), were combined together and the two-drug mixtures (at the fixed-ratio of 1:1) underwent isobolographic evaluation in the mouse 6-Hz corneal stimulation-induced seizure model. Solid lines indicate synergism between the investigated antiepileptic drugs, whereas the dashed lines indicate additive interaction. Interaction indices for the studied two-drug combinations of antiepileptic drugs are presented as vertical columns. White columns illustrate synergistic interaction, whereas stripped columns present additive interactions among the tested drugs.