What is lacosamide?

What is Lacosamide?

Lacosamide is a third-generation antiseizure medication (ASM) that works through a unique mechanism—selectively enhancing slow inactivation of voltage-gated sodium channels—making it distinct from traditional sodium channel blockers like phenytoin and carbamazepine. 1, 2

Mechanism of Action

Lacosamide functions as a voltage-gated sodium channel (VGSC) modulator with a dual mode of action 3:

• Selectively enhances slow inactivation of voltage-gated sodium channels without affecting fast inactivation, unlike traditional sodium channel blockers 1, 2
• Shifts the slow inactivation curve to more hyperpolarized potentials and increases the maximal fraction of channels in the slow inactivated state 1
• Terminates sustained repetitive firing on a time scale of seconds (not milliseconds like other sodium channel blockers) 1
• May interact with collapsin response mediator protein-2 (CRMP-2), though this is a secondary mechanism 4, 5, 6

This unique mechanism makes lacosamide the only antiepileptic drug in clinical practice that exerts its anticonvulsant activity predominantly by selectively enhancing slow sodium channel inactivation. 1

Clinical Indications

Lacosamide is FDA-approved for specific seizure types 7, 8, 9:

• Adjunctive therapy for partial-onset (focal) seizures in adults and children ≥4 years old 2, 9
• Second-line treatment for status epilepticus when benzodiazepines fail 7, 8
• Used in refractory status epilepticus protocols before escalating to anesthetic agents 7

Pharmacokinetics & Drug Interactions

Lacosamide has favorable pharmacokinetic properties 2, 5:

• Nearly 100% oral bioavailability 4
• Minimal plasma protein binding 5
• Renally excreted without significant hepatic metabolism 5
• No clinically relevant drug-drug interactions—does not inhibit or induce cytochrome P450 enzymes 2, 6
• Fast absorption rate with predictable kinetics 2

Dosing & Administration

Available formulations include oral tablets (50 mg, 100 mg, 150 mg, 200 mg) and intravenous preparations 10:

• For chronic epilepsy management: Typical maintenance doses range from 200-400 mg/day in divided doses 5
• For status epilepticus: Administered intravenously as second-line therapy after benzodiazepine failure 7, 8
• Can be given more rapidly than phenytoin with fewer adverse effects 8

Safety Profile

Lacosamide demonstrates a favorable safety profile compared to older ASMs 3, 2, 6:

• Most common adverse events: Dizziness, nausea, and vomiting 5
• Lower incidence of arousal-related adverse events compared to carbamazepine 3
• Does not cause hypotension (unlike phenytoin/fosphenytoin which causes hypotension in ~12% of cases) 8
• No tissue necrosis risk with intramuscular administration (unlike diazepam) 11
• Not neurotoxic to the developing brain—unlike phenobarbital, lacosamide does not cause apoptotic cell death in neonatal animal models 12
• Well tolerated in safety pharmacology and toxicology studies with no genotoxic or carcinogenic effects 6

Advantages Over Traditional ASMs

Lacosamide offers several clinical advantages 3, 8, 13:

• Superior tolerability compared to carbamazepine—switching from carbamazepine to lacosamide significantly reduces elevated gamma-glutamyl transpeptidase (GGT) levels (median 141.5 to 63.5 IU/L) within one month 13
• Abrupt switching from carbamazepine to lacosamide without cross-titration appears safe and effective in preventing seizure recurrence 13
• Does not impair driving performance with continued administration—no clinically meaningful driving impairment observed in chronic use 3
• Lower risk of traffic accidents compared to some other ASMs based on epidemiological data 3

Common Pitfalls to Avoid

• Do not assume lacosamide works like traditional sodium channel blockers (phenytoin, carbamazepine)—its mechanism targeting slow inactivation is fundamentally different 1
• Do not overlook lacosamide as a second-line option in status epilepticus—it has comparable efficacy to valproate and levetiracetam with excellent safety 7, 8
• Do not hesitate to switch from carbamazepine to lacosamide in patients with elevated liver enzymes—the switch can be done abruptly and safely 13
• Do not avoid lacosamide in neonates due to neurotoxicity concerns—unlike phenobarbital, it does not cause apoptotic brain injury 12