Long-term exposure and safety of lacosamide monotherapy for the treatment of partial-onset (focal) seizures: Results from a multicenter, open-label trial.

OBJECTIVE: To assess long-term use and safety of lacosamide (LCM) ≤800 mg/day monotherapy in patients with partial-onset seizures (POS) enrolled previously in a historical-controlled, conversion-to-monotherapy study (SP902; NCT00520741).

METHODS: Patients completing or exiting SP902 with LCM as monotherapy or as adjunctive therapy were eligible to enter this 2-year open-label extension (OLE) trial (SP904; NCT00530855) at a starting dose ±100 mg/day of their final SP902 dose. Investigators could adjust the LCM dose to 100-800 mg/day and add up to two antiepileptic drugs to optimize tolerability and seizure reduction.

RESULTS: Three hundred twenty-two patients received LCM: 210 patients (65.2%) completed and 112 (34.8%) discontinued, most commonly owing to withdrawal of consent (9.3%). Two hundred fifty-eight patients (80.1%) had ≥1 year of and 216 (67.1%) had ≥2 years of LCM exposure, of whom 179/258 (69.4%) achieved LCM monotherapy lasting for any 12-month period, and 126/216 (58.3%) patients exposed for ≥24 months achieved LCM monotherapy for any 24-month period. Total exposure = 525.5 patient-years. The median modal dose was 500 mg/day. Two hundred ninety-two patients (90.7%) achieved LCM monotherapy at some point during the study. Sixty-five of 87 patients who exited and 193/235 who completed SP902 were exposed for ≥12 months, and 43.1% and 78.2%, respectively, achieved LCM monotherapy for ≥12 months. Median LCM monotherapy duration was 587.0 days (2-791 days); 91.0% of patients reported treatment-emergent adverse events, of which the most common were dizziness (27.3%), headache (17.1%), and nausea (14.3%). Compared with the SP902 study baseline, 74.2% of patients had a ≥50% seizure reduction and 5.6% were seizure-free at 24 months.

SIGNIFICANCE: The majority of patients were receiving LCM monotherapy at 0, 12, and 24 months in this OLE. Lacosamide monotherapy (median dose of 500 mg/day) had a safety profile similar to that of adjunctive therapy studies. These results support the use of lacosamide as long-term monotherapy treatment for adults with POS.