Factors influencing response to intravenous lacosamide in emergency situations: LACO-IV study

Status epilepticus (SE) and acute repetitive seizures (ARSs) frequently result in emergency visits. Wide variations in response are seen with standard antiepileptic drugs (AEDs). Oral and intravenous (IV) formulations of lacosamide are approved as adjunctive therapy in the treatment of partial-onset seizures in adults and adolescents. The aim of the retrospective multicenter observational study (LACO-IV) was to analyze data from a large cohort of patients with SE or ARSs of varying severity and etiology, who received IV lacosamide in the emergency setting. Patient clinical data were entered into a database; lacosamide use and efficacy and tolerability variables were analyzed. In SE, IV lacosamide tended to be used mainly in nonconvulsive status epilepticus as second- or third-line treatment. The proportion of patients with no seizures when IV lacosamide was the last drug administered was 76.5% (70.9% SE and 83.7% ARSs). The rate of seizure cessation ≤ 24 h after IV lacosamide administration was 57.1% (49.1% SE and 67.4% ARSs). Of the factors analyzed, a shorter latency from seizure onset to IV lacosamide infusion influenced treatment response significantly. A nonsignificant tendency towards a higher response was seen with lacosamide dose >200mg versus ≤ 200 mg. Analysis of response according to mechanism of action showed no significant differences in response to IV lacosamide in patients receiving prior sodium channel blocker (SCB) or non-SCB AEDs in the overall or SE population; however, in ARSs, a tendency towards a higher response was observed in those receiving non-SCB AEDs. The frequency and nature of adverse events observed were in line with those reported in other studies (somnolence being the most frequent). In the absence of randomized prospective controlled studies of IV lacosamide, our observations suggest that IV lacosamide may be a potential alternative for treatment of SE/ARSs when seizures fail to improve with standard AEDs or when AEDs are contraindicated or not recommended.