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.