Results of a multicenter international study on the efficacy of exalief (eslicarbazepine acetate (ESL)), a newer blocker of voltage-gated sodium channels and T-type voltage gated calcium channels, for adjunctive therapy of refractory partial-onset seizures are presented. A clinical program included phase II (BIA-2093-201) followed by three phase III studies (BIA-2093-301, -302 and -303), each of which was accompanied by an additional open one-year study (301Е, 302Е, 303Е). In three parallel phase III studies patients were randomized to receive ESL in single doses 400, 800, 1200 mg or placebo together with 1 - 3 antiepileptic drugs used in stable doses, with the exception of felbamate and oxcarbazepine. The design of the study included 8-week initial period, double-blind phase (2-week titration period, 12-week maintenance period), 4-week dose reduction period. The results of clinical phase II trials demonstrated the high efficacy and best tolerability profile for single dose titration regimen. Median changes in the frequency of partial-onset seizures were greater (p<0,0001) in patients receiving 800 and 1200 mg ESL (35 and 39%) compared to placebo (15%). The proportion of treatment responders was significantly higher in the groups treated with ESL in doses 800 mg (36%) and 1200 mg (44%) compared to the placebo group (22%). The aversive effects of the drug were of mild or moderate severity. Treatment retention was higher in patients receiving ESL (84,9% of patients completed the 6-month treatment period and 76,6% completed the one-year period). The use of ESL leads to the reduction in partial seizure frequency and the increase in the proportion of treatment responders. The drug has a good tolerability profile.