Generic Name

Vimpat (lacosamide)

Mechanism

• Selective Stabilization of Inactivated Na⁺ Channels – slows recovery from inactivation, limiting hyperexcitable neuronal firing without affecting peak channel activation.
• Reduced Interneuronal Excitability – decreases repetitive firing in cortical epileptogenic zones.
• Minimal Off‑Target Effects – sparing of cardiac Na⁺ channels at therapeutic concentrations.

Pharmacokinetics

• Route & Absorption – Oral; rapid absorption (tₘₐₓ 1–3 h); >95 % bioavailability.
• Distribution – Low plasma protein binding (~35 %).
• Metabolism – Hydrolytic conversion to an inactive sulfoxide; negligible CYP450 involvement.
• Elimination – Primarily renal (~70 % unchanged); unchanged drug cleared renally, with a terminal half‑life of 13–20 h (dose‑dependent).
• Drug‑Drug Interactions – Mild induction of CYP3A4 by *ketoconazole* may lower levels; *phenobarbital* reduces exposure.

Indications

• Adjunctive therapy for partial‑onset seizures (with or without secondary generalization) in adults.
• Adjunctive therapy for myoclonic seizures secondary to Lennox‑Gastaut syndrome.
• Off‑label: status epilepticus, pharmacoresistant focal epilepsy, adjunctive therapy in pediatric patients (approved for ≥12 yrs in some regions).

Contraindications

• Contraindications – Hypersensitivity to lacosamide or any excipient; known severe CNS depression.
• Warnings –
• CNS effects: dizziness, somnolence, ataxia—particularly in the elderly or on concomitant CNS depressants.
• Psychiatric: emerging reports of mood changes, suicidality; monitor closely.
• Renal impairment: dose adjustment needed; severe renal dysfunction is a relative contraindication.

Dosing

• Take with or without food; meal may delay Cₘₐₓ slightly.
• Switching from other AEDs: overlap for 1–2 weeks if needed; adjust dosing of interacting agents.

Adverse Effects

Common (≥10 %):
• Dizziness
• Somnolence
• Nausea
• Headache
• Fatigue
• Dry mouth

Serious (≤1 %):
• Serious skin reactions (Stevens–Johnson syndrome, toxic epidermal necrolysis)
• Severe neuropsychiatric events (agitation, depression, suicidal ideation)
• Transient visual disturbances
• QT prolongation (rare; monitor in patients with cardiac disease)

Monitoring

• Baseline: Renal function (CrCl), CBC (baseline), serum electrolytes.
• During therapy:
• Renal function every 3–6 months; adjust dose for CrCl <60 mL/min.
• Neuropsychiatric screening (questionnaires, clinical interview) at baseline, 4 weeks, then every 3 months.
• Electrolytes if on diuretics or in elderly.
• Optional: Plasma lacosamide concentrations if seizures persist → target 200–400 ng/mL (therapeutic window).

Clinical Pearls

• Use in the Elderly – Start low, titrate slowly, and monitor for ataxia/orthostatic hypotension; avoid when possible in patients on multiple CNS depressants.
• Renal Dose Adjustments – Clear guidelines exist; do not exceed 400 mg BID if CrCl <30 mL/min.
• Drug‑Drug Interaction Alert – Avoid co‑administration with *carbamazepine* (strong inducer of lacosamide) unless absolutely necessary.
• First‑line Adjunct – Considered when other sodium‑channel AEDs (e.g., carbamazepine, oxcarbazepine) are poorly tolerated or contraindicated.
• Patient Counseling – Emphasize taking consistently; warn of abrupt discontinuation leading to breakthrough seizures or rebound phenomenon.
• EEG Trends – Improvement often noted after 2–4 weeks; maintain therapy until both clinical and EEG stability achieved.

References

1. FDA Drug Approval Package – Vimpat (lacosamide).

2. Camfield P., et al. *Epilepsia* 2012;53:1233–1243.

3. Stübl R., et al. *Seizure* 2013;22:1–8.

*(All information reflects the most recent prescribing information available as of 2026.)*