Jennifer Weston, Arif Shukralla, Andrew J McKay, Anthony G Marson

Around half of people with epilepsy will not achieve seizure freedom on their first antiepileptic drug; many will require add-on treatment with another drug. Sometimes multiple treatment combinations are tried to achieve maximum seizure control, although around a third of people do not achieve complete seizure control. Lacosamide is an antiepileptic drug that has been licensed as an add-on treatment for partial epilepsy. To evaluate the efficacy and tolerability of lacosamide when used as an add-on treatment for patients with drug-resistant partial epilepsy. We searched the Cochrane Epilepsy Group's Specialized Register (21 May 2015), the Cochrane Central Register of Controlled Trials (CENTRAL , The Cochrane Library Issue 4, April 2015), MEDLINE (Ovid, 1946 to 21 May 2015), Scopus (1823 to 13 November 2014), ClinicalTrials.gov (21 May 2015) and the WHO International Clinical Trials Registry Platform (ICTRP, 21 May 2015). We imposed no language restrictions. We contacted UCB (sponsors of lacosamide) and experts in the field. Randomised controlled trials of add-on lacosamide in people with drug-resistant partial epilepsy. Two review authors independently assessed trials for inclusion and extracted the relevant data. We assessed the following outcomes: (1) 50% or greater reduction in seizure frequency; (2) seizure freedom; (3) treatment withdrawal for any reason; and (4) adverse events. Primary analyses were intention-to-treat. Summary risk ratios were estimated for each outcome. We included three trials in our review (1311 participants), which were classified as having low risk of bias. All trials were placebo-controlled and assessed doses ranging from 200 mg to 600 mg per day. Trial duration ranged from 24 to 26 weeks. All trials used adequate methods of randomisation and were double-blind. Overall the quality of the evidence was rated as moderate to high. The overall risk ratio for a 50% or greater reduction in seizure frequency for all doses of lacosamide compared with placebo was 1.70 (95% confidence interval (CI) 1.38 to 2.10); for seizure freedom for all doses of lacosamide compared with placebo was 2.50 (95% CI 0.85 to 7.34); and for treatment withdrawal for all doses of lacosamide compared with placebo was 1.88 (95% CI 1.40 to 2.52). Adverse effects significantly associated with lacosamide were abnormal co-ordination (risk ratio (RR) 6.12, 99% CI 1.35 to 27.77), diplopia (RR 5.29, 99% CI 1.97 to 14.23), dizziness (RR 3.53, 99% CI 2.20 to 5.68), nausea (RR 2.37, 99% CI 1.23 to 4.58) and vomiting (RR 3.49, 99% CI 1.43 to 8.54). Adverse effects that were not statistically significant were headache (RR 1.34, 99% CI 0.83 to 2.18), fatigue (RR 2.11, 99% CI 0.92 to 4.85), nystagmus (RR 1.47, 99% CI 0.61 to 3.52) and somnolence (RR 1.44, 99% CI 0.67 to 3.09). This review has shown lacosamide to be effective and fairly well tolerated in the short term when used as add-on treatment for drug-resistant partial epilepsy in adults. Higher doses of lacosamide may be more associated with adverse effects and withdrawal of the drug than lower doses. Additional evidence on children is needed, and longer-term efficacy is unknown.