Different AEDs have different effects on the brain. Some work by raising the levels of certain neurotransmitters in the brain. Others block specific ion channels in the neurons. Many AEDs have several different effects.
Each AED has a generic name and one or more brand names. The generic name is the chemical name for the drug. The brand name is given by the pharmaceutical company that produces the drug.
Common AEDs
The generic names of the drugs available in Canada are listed below. Please click a drug name to read more about that drug.
- Acetazolamide
- ACTH
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Carbamazepine
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Clobazam
- Clonazepam
- Diazepam
- Ethosuximide
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Gabapentin
- Lamotrigine
- Levetiracetam
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Lorazepam
- Nitrazepam
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Phenobarbital
- Phenytoin and fosphenytoin
- Topiramate
- Valproate
- Vigabatrin
Less commonly used drugs
Midazolam
Midazolam is more commonly known by the brand name Apo-Midazolam. It is available through intravenous injection and intramuscular injection (injection into the muscle).
It is not used as a routine anticonvulsant but instead used only in emergency situations for status epilepticus and other acute repetitive seizures, usually after drugs such as diazepam, lorazepam, phenobarbital and phenytoin have failed to stop a prolonged seizure or a cluster of continuous seizures.
Midazolam is also used as a sedative for procedures such as lumbar puncture. Due to its sedating effects, it is often used on a hospital ward or in the intensive care unit.
When used in an emergency situation to stop seizures, midazolam will usually cause fatigue. When used in high doses, midazolam can reduce the instinct to breathe and children may need help with their breathing using a ventilator.
Oxcarbazepine
Oxcarbazepine is more commonly known by the brand name Trileptal. It is available in liquid and tablet form.
It is used for partial seizures, with or without secondary generalization.
Oxcarbazepine tends to have fewer and less severe side effects than carbamazepine. Possible side effects include fatigue, blurred vision, dizziness, and nausea.
Serious possible side effects include allergic reaction, changes in blood sodium and potentially life-threatening skin rash. These side effects are very rare. Your child's doctor can monitor for some of these effects with blood tests. If you notice skin rashes, swelling or other symptoms that concern you, contact your child's doctor immediately.
If a child experiences a hypersensitivity reaction to carbamazepine, there is a 25–30 per cent chance that they will also have a reaction to oxcarbazepine.
Paraldehyde
Paraldehyde is available through injection or through oral or rectal liquid.
It is used only in emergency situations to stop a prolonged seizure or a cluster of seizures. It may be used in status epilepticus. Paraldehyde is not used as a routine AED. It is most often given by rectal administration.
Possible side effects include unsteadiness, drowsiness, nausea, stomach pain and bad breath. Severe possible side effects include coughing, skin rash, fast/difficult breathing, severe weakness, severe stomach cramps, tremors and slow heartbeat. Paraldehyde is almost always used in the hospital.
Primidone
Primidone is a very old AED that is more commonly known by the brand name Apo-Primidone, Myidone, Mysoline or Sertan. It is available through a syrup or tablet.
It is effective against a broad spectrum of seizures, including partial seizures, generalized tonic-clonic seizures and myoclonic seizures. It is not a drug of first choice because of its neurological side effects and is used only occasionally these days. Primidone is converted to phenobarbital in the body.
When first starting primidone, children may experience drowsiness, clumsiness, nausea or vomiting. Primidone is also associated with behavioural changes including hyperactivity, irritability, aggressive behaviour and difficulty sleeping.
As with most drugs, there is a risk of allergic reaction, although this is rare. If your child develops rash or swelling, contact your child's doctor immediately.
A note on off-label use
For drugs to be approved for use by a regulatory agency such as Health Canada or the US Food and Drug Administration (FDA), the manufacturer must conduct clinical trials of the drug. The resulting information about the drug's efficacy, safety and side effects is then submitted to the regulator. The drug is approved only for those conditions and in those groups of patients for which it has been shown to have an effect. These are known as the labelled indications. They are listed on the drug's package insert.
For some conditions, and particularly for children, doctors often prescribe drugs for other indications that are not on the label. This does not mean that the drug is known to be harmful or that it should not be used, but it does mean that the drug has not been formally approved for this particular use. This is usually because no formal clinical trial has been conducted. However, doctors gain experience with drugs outside formal trials as well. For example, lamotrigine is approved as adjunct therapy (to be used in combination with another AED), but in some situations a doctor may decide to use it alone. In other cases, your child's doctor may decide to prescribe a drug that has only been approved for use in adults.
Doctors make these decisions based on the results of new research studies or based on their experience with other patients. You should feel free to ask your child's doctor why they have chosen to prescribe a particular drug off-label, why they believe it is the best choice for your child, and if there have been any studies of this drug in patients like your child.