Safety and efficacy of adjunctive lacosamide among patients with partial-onset seizures in a long-term open-label extension trial of up to 8 years.

Long-term (up to 8 years of exposure) safety and efficacy of the antiepileptic drug lacosamide was evaluated in this open-label extension trial (SP615 [ClinicalTrials.gov identifier: NCT00552305]). Patients were enrolled following participation in a double-blind trial or one of two open-label trials of adjunctive lacosamide for partial-onset seizures. Dosage adjustments of lacosamide (100-800 mg/day) and/or concomitant antiepileptic drugs were allowed to optimize tolerability and seizure reduction. Of the 370 enrolled patients, 77%, 51%, and 39% had >1, >3, or >5 years of lacosamide exposure, respectively. Median lacosamide modal dose was 400mg/day. Common treatment-emergent adverse events (TEAEs) were dizziness (39.7%), headache (20.8%), nausea (17.3%), diplopia (17.0%), fatigue (16.5%), upper respiratory tract infection (16.5%), nasopharyngitis (16.2%), and contusion (15.4%). Dizziness (2.2%) was the only TEAE that led to discontinuation in >2% of patients. Ranges for median percent reductions in seizure frequency were 47-65%, and those for ≥ 50% responder rates were 49-63% for 1-, 3-, and 5-year completer cohorts. Exposure to lacosamide for up to 8 years was generally well tolerated, with a safety profile similar to previous double-blind trials, and efficacy was maintained.