Antiepileptic drugs: what they are, how they work

By Cristiano Antonino On Apr 18, 2023

Antiepileptic drugs (anticonvulsants) help treat epilepsy and other causes of seizures. They can treat other conditions as well, such as anxiety and neuropathic pain

There are several types of anticonvulsant drugs.

What are antiepileptic drugs (anticonvulsants)?

Antiepileptic drugs (formerly known as antiepileptic drugs or anticonvulsants) are prescription drugs that help treat and prevent seizures.

Healthcare professionals may prescribe these drugs to treat other conditions as well.

A seizure occurs when you have a temporary, unstoppable surge of electrical activity in the brain.

This overloads the affected areas of your brain.

It can cause a wide range of symptoms, including:

Abnormal sensations.
Loss of awareness.
Sagging.
Uncontrolled muscle movements (convulsions).

People most commonly associate epilepsy with seizures, but there are many other causes of seizures (often called symptomatic seizures).

Why are these drugs no longer called anticonvulsants?

Healthcare professionals now call these drugs antiepileptic drugs because they help treat and prevent seizures.

While people often associate seizures with seizures, not all seizures involve seizures (jerky movements).

For example, some seizures cause temporary confusion, staring, and/or loss of consciousness or awareness.

Therefore, “antiseizure drugs” is a more accurate term than “anticonvulsants” to describe what these drugs help treat.

List of antiepileptic drugs (anticonvulsants)

Healthcare professionals can prescribe several types of anticonvulsant drugs.

They include:

Brivaracetam (Briviact®).
Cannabidiol (Epidiolex®).
Carbamazepine (Epitol®, Tegretol®).
Cenobamate (Xcopri®).
Clobazam (Onfi®).
Clonazepam (Ceberclon®, Klonopin®).
Eslicarbazepine (Aptiom®).
Ethosuximide (Zarontin®).
Felbamate (Felbatol®).
Phosphenytoin (Cerebyx®).
Gabapentin (Horizant®, Gralise®, Neurontin®).
Lacosamide (Vimpat®).
Levetiracetam (Keppra®, Roweepra®).
Oxcarbazepine (Trileptal®).
Perampanel (Fycompa®).
Phenobarbital (Solfoton®, Luminal®).
Phenytoin (Dilantin®, Phenytek®).
Pregabalin (Lyrica®).
Primidone (Mysoline®).
Rufinamide (Banzel®).
Stiripentol (Diacomit®).
Tiagabine (Gabitril®).
Topiramate (Topamax®, Topiragen®).
Valproate products: Valproate sodium (Depacon®), divalproex sodium (Depakote®), valproic acid (Depakene® and Stavzor®).
Vigabatrin (Sabril®).
Zonisamide (Zonegran®).

All of these drugs have specific uses based on:

The type or types of seizures that occur, such as focal seizures or absence seizures.
The underlying condition that causes the seizures, such as Lennox-Gastaut syndrome or Dravet syndrome.
The age.

Healthcare professionals also divide antiepileptic drugs into two general groups:

Broad-spectrum antiepileptic drugs: These drugs treat a wide variety of seizure types. Providers generally prescribe these first if they are unsure of the seizure type. Some broad-spectrum anticonvulsant drugs include levetiracetam, lamotrigine, zonisamide, and topiramate.
Narrow-spectrum antiepileptic drugs: These drugs mainly treat focal or partial seizures. Some narrow-spectrum anticonvulsant drugs include ethosuximide, pregabalin, gabapentin, and carbamazepine.

What is an antiepileptic drug used for?

Healthcare professionals prescribe antiepileptic drugs to treat epilepsy and symptomatic seizures.

They also prescribe these drugs to prevent and/or treat seizures that occur during or after brain surgery.

Doctors may prescribe anticonvulsant drugs for other conditions not related to seizures.

Some anticonvulsant drugs can help treat:

Anxiety.
Migraine.
Bipolar disorder.
Neuropathic pain.
fibromyalgia.
Restless legs syndrome.
Parkinson’s disease.

Some doctors prescribe zonisamide or topiramate to aid in weight loss.

How do antiepileptic drugs work?

In general, antiepileptic drugs work by controlling the abnormal electrical activity in the brain.

There are many different types of AEDs, and they do it in different ways.

Your brain contains billions of cells known as neurons.

Neurons transmit and transmit chemical and electrical signals to each other.

At any time, neurons may be at rest or may be exciting (activating) or inhibiting (blocking) other neurons.

Seizures occur when a malfunction causes neurons to fire electrical signals uncontrollably.

This causes a domino effect, which means that more and more neurons are involved in the generation of abnormal electrical discharges.

Antiepileptic drugs work in different ways to reduce arousal or promote inhibition of the processes that cause electrical signals.

Specifically, they can act:

Change in electrical activity in neurons by affecting ion channels (sodium, potassium, calcium and/or chloride).
Changing the chemical transmission between neurons by affecting neurotransmitters (such as GABA).
Researchers don’t know exactly how some antiepileptic drugs work.

How long will I need to take an antiepileptic drug?

How long you’ll need to take an anti-seizure drug depends on your unique situation and why you’re taking it.

If you have epilepsy and become seizure free after taking anticonvulsants, your ability to stop the anticonvulsants depends on a number of factors, including:

The type of epilepsy.
The number of AEDs you are taking.
How long have you been without seizures.
When did you first develop epilepsy?
How long did you have epilepsy before you were seizure free.
The number of seizures you had before becoming seizure free.
If you have other neurological conditions.
The presence of abnormal EEG findings.
If you have had surgery for epilepsy.

Together, you and your doctor will decide what is best for you.

What are the side effects of antiepileptic drugs?

Each type of anti-epileptic drug and each brand has different possible side effects.

It’s important to talk to your doctor or a pharmacist about the possible side effects of the specific medication you’re taking.

In general, common side effects of antiepileptic drugs include:

Heachache.
Fatigue.
Dizziness.
Blurred vision.
Nausea.
Weight gain or loss.
Mood changes.

Long-term use of some anticonvulsant drugs can lead to osteoporosis.

For this reason, providers usually recommend supplementing your diet with calcium and vitamin D.

Are antiepileptic drugs effective?

Anticonvulsant drugs can prevent seizures in about 7 out of 10 people who experience them.

However, it may take some time to find the type of medication that works best for you, as everyone is different.

Other treatments can help manage seizures if medications aren’t working, including:

Epilepsy surgery.
Dietary changes, such as the ketogenic diet.
Responsive neurostimulation.
Deep brain stimulation.
Stimulation of the vagal nerve.

What are the possible risks or complications of antiseizure drugs?

Rare but serious complications of antiepileptic drugs include:

Stevens-Johnson syndrome.
Agranulocytosis.
Aplastic anemia.
Liver failure.
Pancytopenia (lack of all three cellular components of blood: red blood cells, white blood cells, and platelets).
Drug-induced delayed multiorgan hypersensitivity syndrome (an allergic reaction affecting the skin, liver, lymphatic system and other body systems).
Psychosis.
Lupus.

Other possible complications include:

Drug interactions.
Toxicity.
Risk of suicidal thoughts or behaviour.

Drug interactions

Adverse drug interactions occur most commonly with older generation anticonvulsant drugs.

This is because they can affect liver enzymes, either making too many of them or blocking their production.

This can affect how your body breaks down (uses) other medications you’re taking.

Be sure to tell your doctor about all medications you are taking before starting an anti-seizure drug, including prescriptions, over-the-counter medications, and supplements.

Also, if you’re already taking an anti-epileptic drug, be sure to tell your provider before starting any new medication.

Toxicity

Anticonvulsant drug toxicity can occur if you take too much of the drug at once, either accidentally or knowingly.

Symptoms include:

Confusion.
Nystagmus.
Ataxia.
Slow and shallow breathing (respiratory depression).
Some anticonvulsant drugs can also cause arrhythmia (irregular heartbeat).
Antiepileptic drug toxicity is a medical emergency.

Call Emergency Number or go to the nearest emergency room if you or a loved one has these symptoms.

Without treatment, it can lead to coma or death.

It’s important to take your medications exactly as prescribed by your doctor to avoid toxicity.

Make sure you keep your medications in a safe place away from children and pets.

Are Antiepilectic safe during pregnancy?

Medical guidelines recommend keeping the current antiepileptic drug during pregnancy, as the benefits of taking it outweigh the potential risks to the fetus.

Stopping antiepilectic can lead to breakthrough seizures and status epilepticus, which can be harmful to you and a developing fetus.

There is a lack of research into which antiepilectic are safest during pregnancy.

Some antiepileptic drugs (such as valproic acid) during pregnancy may increase the risk of serious birth defects and some cognitive problems.

It’s important to discuss the best anti-epileptic drug for you with your doctor before becoming pregnant.

If you have any questions or concerns about taking an anti-seizure drug while pregnant, be sure to talk to your doctor.

Anticonvulsant drugs are an important part of treating epilepsy and symptomatic seizures.

It can take some time to find the anti-epileptic drug that works best for you.

Talk to your doctor about any concerns or questions you have.

They are available to help.

Bibliographical references

Centers for Medicare & Medicaid Services (CMS). Anticonvulsant Medications: Use in Adults. (https://www.cms.gov/Medicare-Medicaid-Coordination/Fraud-Prevention/Medicaid-Integrity-Education/Pharmacy-Education-Materials/Downloads/ac-adult-factsheet11-14.pdf) Accessed 2/3/2023.
Springer C, Nappe TM. Anticonvulsants Toxicity. (https://www.ncbi.nlm.nih.gov/books/NBK537206/) [Updated 2022 Aug 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Accessed 2/3/2023.
Subbarao BS, Silverman A, Eapen BC. Seizure Medications. (https://www.ncbi.nlm.nih.gov/books/NBK482269/) [Updated 2022 Jul 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Accessed 2/3/2023.

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