Lacosamide (Vimpat)
Generic Name: Lacosamide
Brand Name: Vimpat
Drug Class: Functionalized amino acid; sodium channel modulator (enhances slow inactivation)
Primary Uses: Focal-onset seizures; generalized tonic-clonic seizures (adjunctive)
What is Lacosamide?
Lacosamide is a newer anti-seizure medication used for focal seizures and, alongside other medications, for generalized tonic-clonic seizures. It is approved for children 4 years and older and is also available as an IV formulation, which is useful if a child cannot take medication by mouth.
How It Works
Lacosamide enhances the “slow inactivation” of sodium channels in brain cells. This makes it harder for overactive neurons to keep firing rapidly, without shutting down normal brain activity1.
Who Might Take This Medication?
Lacosamide is FDA-approved for:
- Focal (partial) onset seizures, ages 4 and up
- Generalized tonic-clonic seizures, as add-on therapy, ages 4 and up
It is also commonly used off-label in younger children and for other seizure types when other medications have not worked well2.
Lacosamide can slightly slow electrical conduction through the heart (PR interval prolongation). This is usually mild and without symptoms, but:
- An ECG may be ordered before starting and after dose increases, especially in children with heart conditions or on other medications that affect heart rhythm3
- Watch for fainting, palpitations, or a very slow or irregular pulse
Common Side Effects
Most side effects are dose-related and often improve over time or with slower titration.
Common side effects:
- Dizziness
- Drowsiness or fatigue
- Nausea
- Headache
- Double or blurred vision
- Unsteadiness, especially with dose increases
- Doses are usually given about 12 hours apart
- Can be taken with or without food
- Slower titration can reduce dizziness and unsteadiness
Serious Side Effects
- Fainting, palpitations, or a very slow or irregular heartbeat
- Chest pain or shortness of breath
- New rash, hives, or swelling of the face, lips, or tongue
- New or worsening sadness, anxiety, or thoughts of self-harm
- Unusual movements different from your child’s typical seizures
If your child or anyone in your family is having thoughts of suicide or self-harm, call or text 988 (Suicide and Crisis Lifeline), available 24/7.
Medication Interactions
Lacosamide has relatively few drug interactions because it has minimal effect on liver enzymes1. However, combining it with other sodium channel-blocking medications (carbamazepine, oxcarbazepine, phenytoin, lamotrigine) can increase dizziness and unsteadiness even when seizure control improves.
Always tell your child’s full care team, including dentists and pharmacists, about all medications and supplements your child takes.
Monitoring
Your doctor may order:
- ECG: before starting and after dose increases, especially with heart conditions or other PR-prolonging medications3
- Lacosamide blood levels: if seizures are uncontrolled, side effects appear, or weight changes significantly
- Routine growth and weight checks
Administration
Give this medicine:
- Exactly as prescribed, twice daily about 12 hours apart
- With or without food
- Dose is typically weight-based and may change as your child grows
Pregnancy and Breastfeeding
Lacosamide has not yet been thoroughly studied in pregnancy4. If pregnancy is being planned or occurs, talk with the epilepsy team about a pregnancy registry. Untreated seizures also carry risks, so this is a decision to make together with the care team, not on your own.
Stopping This Medication
Do not stop lacosamide suddenly. Stopping abruptly can cause seizures to return, sometimes more severe than before, including prolonged seizures (status epilepticus). If discontinuation is needed, your doctor will create a gradual tapering plan.
Frequently Asked Questions
What if my child misses a dose?
Give it as soon as you remember. If it’s almost time for the next dose, skip the missed one. Do not double up. Call the epilepsy team if several doses are missed.
How long does it take to work?
Steady levels are reached within a few days, but it may take weeks to months at a stable dose to judge effectiveness.
Are there food restrictions?
No. Lacosamide can be taken with or without food.
Will it affect my child’s weight?
Weight changes are not a common side effect of lacosamide.
Is long-term use safe?
Yes. Lacosamide has been studied long-term in children and adults and is generally well tolerated2. Regular follow-up with the epilepsy team continues, as with any long-term medication.
All of the possible uses, cautions, side effects, or interactions of this drug are not covered in this handout. If you want more information about this medication, ask your child’s doctor, pharmacist, or nurse.
This information is for educational purposes only and does not replace medical advice. Always consult your healthcare provider about medications and treatment decisions.