Lacosamide is a functionalized aminoacid that was synthesized during the development of anticonvulsant drug candidates and has displayed antinociceptive properties in inflammatory and neuropathic pain. Lacosamide displays a unique mechanism of action in that it seemingly selectively stabilizes channels into the slow- inactivated state. Lacosamide inhibited currents from Nav1.3, Nav1.7, and Nav1.8, but only after prolonged depolarizations, consistent with an enhancement in slow-inactivation with no effect on fast inactivation. Furthermore, lacosamide was better able to discriminate between resting and inactivated channels compared to lidocaine or carbamazepine, thus likely allowing for improved selectivity over neurons with a depolarized membrane potential, with little tonic block.