Lacosamide

Lacosamide is an antiepileptic drug available in several formulations, each with specific age and weight approvals. Here is the full range of supported uses:

• Partial-onset seizures: Vimpat (tablets, oral solution, and injection) is approved for patients 1 month of age and older. Lacosamide tablets, oral solution, and injection are approved for patients 4 years of age and older. Motpoly XR (extended-release capsule) is approved for adults and pediatric patients weighing at least 50 kg.
• Primary generalized tonic-clonic seizures (as add-on therapy): All formulations are approved for this use in patients 4 years of age and older (or weighing at least 50 kg for Motpoly XR), used alongside other seizure medications.

Lacosamide targets voltage-gated sodium channels — tiny gatekeepers in nerve cell membranes that control electrical signals. It enhances a process called slow inactivation, which helps put overactive channels into a resting state. This stabilizes overexcited nerve cell membranes and prevents them from firing repeatedly, which is what drives seizure activity. The exact way this translates to seizure control in people is still being studied, but the electrical effect is well established in laboratory research.

Lacosamide tablets and oral solution are taken twice daily, with or without food. Motpoly XR extended-release capsules are taken once daily and must be swallowed whole — never opened, chewed, or crushed. The IV injection form is only used in a clinical setting when a patient temporarily cannot swallow medication. In children, the dose is calculated based on body weight. Doses are increased slowly — no more than once per week — to find the right balance of seizure control and tolerability. Always follow your prescriber's exact schedule and never stop or adjust your dose on your own.

The most common side effects include:

• Dizziness — the most frequently reported, especially during the dose-increase phase
• Headache
• Double vision (diplopia)
• Nausea and vomiting
• Drowsiness (somnolence)
• Blurred vision
• Unsteady movement or coordination problems (ataxia)
• Fatigue

More serious reactions — including heart rhythm changes, fainting, suicidal thoughts, and a rare severe allergic reaction called DRESS — require immediate medical attention. Contact your doctor or seek emergency care if any of these occur.

• Suicidal thoughts and behavior: Like all antiepileptic drugs, lacosamide raises the risk of suicidal thinking or behavior. Watch for new or worsening depression, mood changes, or thoughts of self-harm — and report them to a doctor right away. This risk can appear within the first week of treatment.
• Heart rhythm problems: Lacosamide can slow electrical conduction in the heart. Rarely, this has caused serious arrhythmias, cardiac arrest, and death, especially in people with pre-existing heart conditions or those taking other heart medications. An ECG is recommended before starting treatment in at-risk patients.
• Dizziness and coordination problems: These are common, especially during dose increases. If you receive a loading dose, it should be given under medical supervision.
• DRESS (severe allergic reaction): A rare but potentially life-threatening reaction involving fever, rash, swollen lymph nodes, and organ involvement. Stop lacosamide and seek care immediately if these symptoms appear.
• Do not stop suddenly: Lacosamide must be tapered off gradually over at least one week to reduce the risk of a sudden increase in seizures.
• Fainting (syncope): Cases have been reported, some linked to heart rhythm changes or blood pressure shifts.

Lacosamide can interact with several medications, particularly those affecting the heart or liver enzymes:

• Sodium channel blockers, beta-blockers, calcium channel blockers, and potassium channel blockers: Combining any of these with lacosamide raises the risk of serious heart conduction problems, including abnormally slow heartbeat or dangerous rhythms.
• Other antiepileptic drugs that block sodium channels: These can add to lacosamide's effect on PR interval (a measure of heart conduction time), increasing cardiac risk.
• Strong CYP3A4 or CYP2C9 inhibitors (certain antibiotics, antifungals, and other drugs that slow liver enzyme activity): In people with kidney or liver impairment, these can raise lacosamide blood levels significantly, possibly requiring a dose reduction.

This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.

• Tell your doctor if you have any heart condition, including heart block, arrhythmias, sick sinus syndrome, heart failure, or structural heart disease — lacosamide requires extra caution in these cases.
• Tell your doctor about all medications you take, especially any heart or seizure medications.
• Tell your doctor if you have kidney disease — dose adjustment is needed for severe kidney impairment, and lacosamide is effectively removed by hemodialysis.
• Tell your doctor if you have liver disease — dose adjustment is needed for mild to moderate liver impairment, and lacosamide is not recommended in severe liver impairment.
• Tell your doctor if you are pregnant or trying to become pregnant — animal studies show potential harm to a developing baby. Enroll in the NAAED Pregnancy Registry (1-888-233-2334) if you take lacosamide while pregnant.
• Tell your doctor if you are breastfeeding — lacosamide is present in breast milk and has been linked to increased sleepiness in nursing infants. Monitor your baby closely.
• Older adults should start at lower doses and be monitored carefully, as they are more likely to have heart conduction issues, reduced kidney and liver function, and multiple medications that can interact.
• Safety and effectiveness have not been established in infants younger than 1 month of age (for Vimpat) or younger than 4 years for most other formulations.

Taking more than twice the maximum recommended daily dose has been associated with dizziness, nausea, generalized tonic-clonic seizures, confusion, decreased consciousness, heart rhythm abnormalities, cardiogenic shock, cardiac arrest, and coma. Fatalities have occurred after overdoses of several grams. There is no specific antidote — contact a Certified Poison Control Center immediately and seek emergency care. Hemodialysis can remove a significant amount of lacosamide from the blood and may be used in serious cases.

Lacosamide's seizure-reducing effect is correlated with its concentration in the blood — higher exposure generally means greater reduction in seizure frequency. However, doses beyond the maximum recommended amount do not appear to provide additional benefit for most people. On the heart, lacosamide causes a small, dose-related increase in the PR interval (the time it takes an electrical signal to travel from the upper to lower chambers of the heart), though it does not prolong the QTc interval or meaningfully affect QRS duration at recommended doses.

Lacosamide is almost completely absorbed when taken by mouth — its oral bioavailability is approximately 100% — and food does not affect how much is absorbed. Blood levels peak roughly 1 to 4 hours after an oral dose. The drug has a half-life of about 13 hours, meaning it takes about 13 hours for the body to clear half the dose, and steady levels are reached after about 3 days of twice-daily dosing. Lacosamide is mainly eliminated through the kidneys (about 95% in urine), and its levels can build up in people with severe kidney disease or moderate liver disease, requiring dose adjustments. It is minimally bound to proteins in the blood (less than 15%), meaning most of it circulates freely and can be removed efficiently by hemodialysis if needed.

Store at 20°C to 25°C (68°F to 77°F); excursions permitted between 15°C to 30°C (59°F to 86°F). Do not freeze VIMPAT injection or oral solution.