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

Summary 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 ( SP 902; NCT 00520741). Methods Patients completing or exiting SP 902 with LCM as monotherapy or as adjunctive therapy were eligible to enter this 2‐year open‐label extension ( OLE ) trial ( SP 904; NCT 00530855) at a starting dose ±100 mg/day of their final SP 902 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 SP 902 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 SP 902 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 .