Intravenous lacosamide in refractory seizure clusters and status epilepticus: comparison of 200 and 400 mg loading doses.

Background: The treatment of refractory status epilepticus (RSE) remains largely empirical. Lacosamide (LCM) is a new anticonvulsant available in intravenous (IV) form, but its optimal dosing regimen for the treatment of RSE is unknown. We compared safety and efficacy of two loading doses: 200 and 400 mg.

Methods: Prospective observational study of all patients who received IV LCM for RSE or seizure clusters between October 2010 and December 2012. A first group received an IV load of 200 mg of LCM. After the initial part of the study, and due to poor results with this dosage, a second group received a loading dose of 400 mg. Outcome measures included response rate, time to response, and adverse events.

Results: There was a trend in favor of a higher response rate to LCM in the 400 mg group [7/14 (50 %) vs. 2/11 (18 %), respectively; p = 0.2]. Early responses (occurring within 3 h of initiation of LCM) were significantly more frequent in the 400 mg group [4/14 (28 %) vs. 0/11 (0 %); p = 0.026]. Overall, 9/25 patients (36 %) responded to LCM and seizures were terminated in eight more patients (32 %), by adding other anticonvulsants. The following adverse events were attributed to LCM: myoclonus and confusion, increase in seizure frequency, vertigo, ataxia, and an asymptomatic increase in liver enzymes level. All occurred in the 200 mg group. No skin rash, renal, cardiac, or hemodynamic side effects were observed in any group.

Conclusions: In this small prospective observational study, an initial dose of 400 mg of IV LCM was associated with a higher proportion of early termination of RSE and with a trend toward a higher response rate.