What You Need to Know About Lacosamide Drug Interactions

If you're taking Lacosamide (brand name Vimpat) for seizures, it's important to understand how it interacts with other medications, supplements, and even certain foods. While Lacosamide has fewer drug interactions than many older seizure medications, there are still some important combinations to watch out for.

This guide covers the major and moderate interactions you and your doctor should be aware of. For background on what Lacosamide is and how it works, see What Is Lacosamide? and How Does Lacosamide Work?

How Drug Interactions Work

Drug interactions happen in several ways:

• Pharmacokinetic interactions: One drug changes how another is absorbed, broken down, or eliminated by the body. This can raise or lower blood levels of either drug.
• Pharmacodynamic interactions: Two drugs have additive or conflicting effects on the body — for example, two drugs that both slow heart conduction.

Lacosamide is partially metabolized by the liver enzyme CYP2C19, and to a lesser extent by CYP3A4 and CYP2C9. It's not a significant enzyme inducer or inhibitor, which is one reason it has fewer interactions than drugs like Carbamazepine or Phenytoin.

Major Drug Interactions

These combinations require close monitoring or may need to be avoided:

Other Sodium Channel-Blocking AEDs

Combining Lacosamide with other seizure medications that block sodium channels can increase the risk of side effects, especially cardiac conduction problems and CNS depression:

• Carbamazepine (Tegretol)
• Oxcarbazepine (Trileptal)
• Phenytoin (Dilantin)
• Lamotrigine (Lamictal)
• Eslicarbazepine (Aptiom)

Using these together isn't necessarily prohibited — many patients take Lacosamide as add-on therapy alongside another AED. But your doctor will monitor you more closely for dizziness, double vision, unsteadiness, and heart rhythm changes.

Drugs That Prolong the PR Interval

Since Lacosamide can prolong the PR interval on an EKG, combining it with other medications that have the same effect increases the risk of serious cardiac conduction problems like AV block. Watch out for:

• Beta-blockers: Metoprolol (Lopressor), Atenolol (Tenormin), Propranolol (Inderal)
• Calcium channel blockers: Diltiazem (Cardizem), Verapamil (Calan)
• Digoxin (Lanoxin)
• Certain antiarrhythmics: Amiodarone, Flecainide

If you take any of these medications, your doctor may want to do an EKG before starting Lacosamide and periodically during treatment.

CYP3A4 and CYP2C9 Inhibitors

Strong inhibitors of these liver enzymes can modestly increase Lacosamide blood levels, though this is generally not clinically significant at standard doses. Examples include:

• Fluconazole (Diflucan)
• Ketoconazole
• Clarithromycin

Moderate Interactions

CYP2C19 Inhibitors

Since Lacosamide is partially metabolized by CYP2C19, drugs that inhibit this enzyme may slightly increase Lacosamide exposure:

• Omeprazole (Prilosec) — a common acid reflux medication
• Fluconazole (Diflucan) — an antifungal
• Fluvoxamine (Luvox) — an antidepressant

In most cases, this interaction is mild, but your doctor should be aware of it.

CNS Depressants

Combining Lacosamide with other medications that cause drowsiness can increase sedation and impair coordination:

• Opioid pain medications: Oxycodone, Hydrocodone, Morphine
• Benzodiazepines: Lorazepam (Ativan), Clonazepam (Klonopin), Diazepam (Valium)
• Sleep medications: Zolpidem (Ambien), Eszopiclone (Lunesta)
• Muscle relaxants: Cyclobenzaprine (Flexeril), Tizanidine (Zanaflex)
• Certain antihistamines: Diphenhydramine (Benadryl)

Use caution with these combinations. Your doctor may adjust doses or recommend closer monitoring.

Supplements and Over-the-Counter Products

Always tell your doctor about any supplements or OTC products you take:

• St. John's Wort: This herbal supplement can affect liver enzymes and may alter Lacosamide levels. It's also known to interact with many other medications.
• Melatonin: Generally considered safe, but may add to drowsiness.
• CBD products: CBD can inhibit several liver enzymes and may affect the levels of antiepileptic drugs including Lacosamide. Tell your doctor if you use CBD.

Food and Drink Interactions

• Food: Lacosamide can be taken with or without food. No significant food interactions.
• Alcohol: Avoid or limit alcohol. Lacosamide and alcohol are both CNS depressants, and combining them can increase dizziness, drowsiness, and impaired coordination. Alcohol may also lower the seizure threshold, making seizures more likely.
• Grapefruit: While grapefruit is a known CYP3A4 inhibitor, its effect on Lacosamide is not considered clinically significant at normal consumption levels.

What to Tell Your Doctor

Before starting or changing any medication while on Lacosamide, make sure your doctor knows about:

• All prescription medications you take — especially heart medications and other seizure drugs
• Over-the-counter medications, including pain relievers and allergy medications
• Herbal supplements and vitamins
• CBD products
• How much alcohol you consume

It's also a good idea to use one pharmacy for all your prescriptions. Your pharmacist can flag potential interactions automatically.

Final Thoughts

One of Lacosamide's advantages is its relatively clean interaction profile compared to older AEDs. But "fewer interactions" doesn't mean "no interactions." The most important ones to watch are combinations with other sodium channel blockers, heart medications that affect the PR interval, and CNS depressants.

Stay in touch with your doctor, keep an updated medication list, and don't hesitate to ask your pharmacist about potential interactions when filling any new prescription.

For more information, explore our guides on Lacosamide side effects and how to save money on Lacosamide.