Antiepileptics Health Article

Definition

Antiepileptic drugs are medicines that reduce the frequency of epileptic seizures.

This class of drugs includes some drugs that have other uses as well. Phenobarbital is a barbiturate. Barbiturates were once widely used as sleeping pills and are still used in anesthesia for surgery. Clonazepam, clorazepate, and diazepam are members of the benzodiazepine group of drugs and are best known for their use as tranquilizers. Phenytoin is used both to control epileptic seizures and to control irregular heart beats.

Description

There are several different types of epilepsy. Different drugs work best on different types of epilepsy. Following is a list of some of the drugs and their uses:

• topamax (Topiramate), keppra, and ACTH: for infantile spasms (IS)
• ativan: for status epilepticas
• phenobarbital: widely used for tonic-clonic but effective in all forms of epilepsy
• phenytoin (Dilantin): used in tonic-clonic and psychomotor epilepsy
• ethosuximide (Zarontin): used to treat absence seizures
• methsuximide (Celontin): used to treat absence seizures
• zonisamide (Zonegran): used to treat partial seizures
• clonazepam (Klonopin): a benzodiazepine, used to treat absence, myoclonic, and akinetic seizures
• clorazepate (Tranxene): a benzodiazepine used to treat partial seizures
• diazepam (Valium): a benzodiazepine used for treatment of status epilepticus but effective against all forms of epilepsy
• primidone (Mysoline, Myidone, Sertan): useful for tonic-clonic, psychomotor, and focal epilepsy
• valproic acid and sodium valproate (Depakene, Depakote): used to treat all types of generalized seizures
• carbamazepine (Carbatrol, Tegretol): used in treatment of tonic-clonic, mixed, and psychomotor seizures
• felbamate (Felbatol): used primarily in adults but may be used to treat seizures associated with Lennox-Gastaut syndrome
• oxcarbazepine (Trileptal): for treatment of complex-partial, simple-partial, and focal seizures
• lamotrigine (Lamictal): used primarily in adults to treat simple and complex partial seizures but may be used to treat seizures associated with Lennox-Gastaut syndrome in children

General use

Although epilepsy is a collective term for a variety of different types of seizures, all forms of epilepsy start with a random discharge of nerve impulses into the brain. Antiepileptic drugs act by either raising the seizure threshold or by limiting the spread of impulses from one nerve to another inside the brain. As of 2004 the exact mechanism of action is not understood, but there are theories about how some of these drugs work.

Phenobarbital appears to act by slowing down all parts of the brain.

Hydantoins, the class that includes phenytoin, mephenytoin, and ethotoin, seem to work by reducing the flow of sodium into and out of nerve cells. This makes the cells less likely to send out spontaneous impulses, which are the beginning of an epileptic seizure.

Succinimides (ethosuximide, methsuximide, phensuximide) elevate the seizure threshold and make it harder for a nerve impulse to spread from one nerve to another.

Zonisamide may work in a manner similar to the hydantoins, by restricting sodium flow, but some studies contradict this theory.

Benzodiazepines may work by stimulating some brain chemicals that normally slow down nerve function, but the exact mechanism is not known.

Felbamate is similar to the tranquilizer meprobamate (Equanil, Miltown) and may work by blocking the effects of some of the brain chemicals that stimulate the nervous system.

Precautions

Antiepileptic drugs have a large number of side effects and possible adverse effects. To work best, the blood levels of drugs must be kept within a fairly narrow range. Patients should be seen by a qualified physician on a regular basis and, if required, have their blood tested routinely. Too high a blood level of these drugs is likely to cause toxic reactions, while a level that is too low may lead to seizures.

Side effects

Most anticonvulsant medications cause some drowsiness and stomach upset. The following list gives some of the common adverse effects of the various classes of drugs. Parents should consult specific references for more comprehensive lists.

Barbiturates cause the following side effects:

• clumsiness
• dizziness
• constipation
• depression
• faintness

Benzodiazepines cause the following side effects:

• fatigue
• abnormal behavior which can include hallucinations and agitation
• slowed breathing and slowed heart rate
• increased or decreased appetite
• rash and itching

Hydantoins cause the following side effects:

• confusion
• dizziness
• growth of the gums
• severe skin reactions
• stuttering and trembling

Succinimides cause the following side effects:

• dizziness and loss of balance
• severe skin reactions
• depression
• headache
• aggressive behavior

Valproic acid and sodium valproate cause the following side effects:

• stomach and intestinal discomfort
• weight gain or loss
• hair loss
• menstrual bleeding changes
• trembling