Fig 1. Anticonvulsant effects of gabapentin (GBP), lacosamide (LCM), levetiracetam (LEV), pregabalin (PGB) and retigabine (RTG) in the 6-Hz corneal stimulation-induced seizure model in mice.

Doses of the antiepileptic drugs were transformed to logarithm to the base 10 and the protection of animals from 6-Hz corneal stimulation-induced seizures was transformed to probits, according to the log-probit method. Dose-response effects of the studied antiepileptic drugs were linearly related that allowed for calculating the ED₅₀ values ± S.E.M. for all the tested drugs in the 6-Hz corneal stimulation-induced seizure model. Each data point corresponds to probit of mice protected (n = 8 mice/data point) from the 6-Hz corneal stimulation-induced seizures at a given logarithm of dose (in mg/kg). Intersections with the dashed line at 5 probit (50% effect) reflect approximate ED₅₀ values of GBP, LCM, LEV, PGB and RTG, when administered alone. Test for parallelism of dose-response relationship lines for two antiepileptic drugs in the selected combinations was performed as recommended elsewhere [49].