Long-term adjunctive lacosamide treatment in patients with partial-onset seizures

Objective To evaluate long‐term (up to 5.5 years) safety, seizure reduction, and maintenance of efficacy of the antiepileptic drug (AED) lacosamide as adjunctive treatment in an open‐label extension trial (SP774; ClinicalTrials.gov: NCT00515619). Methods Three hundred and seventy‐six adults with partial‐onset seizures taking 1–3 AEDs enrolled following completion of a double‐blind trial of adjunctive lacosamide. During open‐label treatment, dosage of lacosamide (100–800 mg/day) and/or concomitant AEDs could be adjusted to optimize tolerability and seizure control. Results Kaplan–Meier estimates of patient retention were 74.5% at 12 months, 52.9% at 36 months, and 40.6% at 60 months; median open‐label treatment duration was 1183 days (~3.2 years). The most frequently reported treatment‐emergent adverse events were dizziness (24.2%), headache (14.4%), diplopia (13.8%), and nasopharyngitis (13.8%); 9.0% of patients discontinued due to adverse events, most commonly dizziness (1.3%). Median percent reduction in 28‐day seizure frequency from baseline of the double‐blind trial was 49.9% overall, 55.4% for 1‐year completers, and 62.3% for 3‐year completers. Overall, 50.0% of patients were considered ≥50% responders (achieved ≥50% reduction in 28‐day seizure frequency); 55.9% of 1‐year completers and 63.0% of 3‐year completers were ≥50% responders. Conclusion In eligible patients who entered the open‐label extension trial, lacosamide was generally well tolerated. For most patients within each yearly completer cohort, seizure reduction was maintained over time.