A Cochrane review included 4 RCTs with a total of 1146 adults with drug-resistant partial epilepsy. Eslicarbazepine was given for 18 weeks at two trials, 16 weeks in one trial and 14 weeks in one trial, at doses of 400 mg, 800 mg and 1200 mg once daily. The efficacy outcome was 50% or greater reduction in seizure frequency when compared to placebo. The overall relative risk (RR) for reduction in seizure frequency was 1.86 (95% CI 1.46 to 2.36, NNT 6.7). Subgroup analyses showed that higher doses of eslicarbazepine were associated with 50% or greater reductions in seizure frequency (400 mg: RR 1.22, 95% CI 0.80 to 1.85; 800 mg: RR 2.00, 95% CI 1.49 to 2.68; 1200 mg: RR 2.13, 95% CI 1.59 to 2.84). Dose regression analysis showed evidence that eslicarbazepine reduced seizure frequency with an increase in efficacy with increasing doses. Eslicarbazepine was significantly associated with seizure freedom (RR 3.04, 95% CI 1.44 to 6.42). Participants seemed more likely, albeit not significantly, to have eslicarbazepine withdrawn for adverse effects (RR 2.26, 95% CI 0.98 to 5.21). Subgroup analyses assessing treatment withdrawal with different doses of eslicarbazepine suggested a higher withdrawal rate with higher doses (400 mg: RR 2.12, 95% CI 0.53 to 8.48; 800 mg: RR 2.61, 95% CI 1.08 to 6.27; 1200 mg: RR 4.32, 95% CI 1.82 to 10.26). The following adverse effects were associated with eslicarbazepine: dizziness (RR 3.09, 99% CI 1.76 to 5.43), nausea (RR 3.06, 99% CI 1.07 to 8.74), and diplopia (RR 3.73, 99% CI 1.19 to 11.64).
Comment: The quality of evidence is downgraded by study quality (more than 20% drop-out rate, short follow-up time).