Drug Therapy
Many seizure disorders are controlled by various types of anti-seizure medications (sometimes called anti-convulsants or anti-seizure drugs [AEDs]). As well, different types of seizures require different medications. Many of the drugs may 7produce numerous adverse side effects. At least 20% of all patients with epilepsy have uncontrolled seizures and many suffer adverse side effects from anti-seizure drug(s). Therefore, there is a need to develop new drugs. Epilepsy medication may be prescribed alone or in combination. If a person has more than one type of seizure, s/he may have to take more than one type of drug to gain control. However, physicians try to control seizures with a single medicine if they can. In the majority of countries, between ten to twenty drugs are currently approved for the treatment of epilepsy.
When to Start Anti-Seizure Drugs
It is essential that, before anti-seizure drug therapy is started, a correct diagnosis is made. A clear distinction between epileptic and non-epileptic attacks is important because the label of "epilepsy" has crucial medical, therapeutic and social implications (Laidlaw et al., 1993, p. 523). The variable prognosis of epilepsy makes it difficult to decide when to start drug treatment in the individual patient or when to stop. The decision to start treatment in an individual patient should take into account not only the number of attacks experienced, but also the circumstances in which they occurred, the presence or absence of precipitating factors, the type and severity of the attacks, whether or not there are any accompanying neurological, psychiatric or social problems, and whether the patient wants treatment (Laidlaw et al., 1993, p. 424). The risk of reoccurrence of a seizure is greater after two seizures than after one. Drug therapy offers symptomatic benefit, but it has yet to be proved that it achieves more than this.
Resistance to Medication
Approximately
- 50% of seizures are eliminated by medication,
- 30% of seizures are reduced in intensity and frequency by medication,
- 20% of seizures are resistant to medication.
Reaction to a given drug varies from one person to the next. Medication that works for one person with epilepsy will not necessarily work for another. Also, some drugs will reach a therapeutic, seizure-preventing level in a patient's bloodstream more quickly than other drugs. For these reasons, it may take some time to customize the dosage and/or choice of drug(s).
Blood Level Monitoring
Anticonvulsant drug level testing can help a physician achieve seizure control by monitoring the presence of a medication in a patient's bloodstream.
The bloodstream is the pathway to the brain, that leads medication to the centers of the brain where seizures begin. If a drug's blood level is too low, seizures may occur and the dosage will have to be increased. Conversely, too high a drug level may cause a patient to experience side effects, such as drowsiness or confusion. This necessitates a reduction in the dosage or, possibly, a change to a different medication.
Generally, drug level testing should be performed during the course of a treatment program. Subsequent tests are carried out if there are changes in control, or if side effects occur.
History of Medications
For over 100 years, various kinds of medications have been used to treat seizure disorders.
1861 —Bromides — The first medication used to provide control for seizures; however, severe side effects occurred. The bromides extracted a heavy cost in terms of toxicity.
1912 —Phenobarbital — This medication was as effective as bromides, however easier to administer and less toxic. There were many side effects with this drug.
1936 —Phenytoin — Known as the 'miracle' drug of its day. This drug was used as a first choice, or when phenobarbital failed. It was one of the most widely used drugs.
1964 —Valporate — The discovery of valporate's effectiveness as an anti-seizure drug created a new therapeutic paradigm. This drug was thought to be effective in enhancing y-aminobutyric acid (GABA) in the nervous system, and became one of the first drugs in which a mode of action was proposed. This drug has been licensed in the UK for clinical use since 1973, and in the USA since 1978.
NOW — New medications more specific to GABA (a major inhibitory neurotransmitter involved in motor control) are available. GABA began the rational scientific era in the development of anti-seizure drugs. Other "rational" targets are the voltage-dependent sodium channel, and the glutamate receptors.
Pregnancy and Anti-Seizure drugs:
Pregnancy raises special concerns for women taking anti-seizure medications. If you can, talk to your doctor before you become pregnant about how to handle your treatment.
More than 90% of women with epilepsy give birth to normal, healthy infants. However, there are risk factors that must be taken into consideration when a woman with epilepsy considers having a baby. It is important that women do not stop taking medication without medical advice.
Here are some important facts:
- All women have a 2-3% risk of having a child with a birth defect. The risk is higher in women with epilepsy, and is estimated at 4-6%.
- anti-seizure drugs and/or genetic factors may have an effect on the pregnancy.
- Taking folic acid before and during pregnancy may decrease the risk of birth defects and is recommended by many physicians for women of child-bearing age.
- Pregnancy changes the way medications are processed in the body, so regular checks and possible adjustments to dosage may be required.
- The frequency of seizures may increase during pregnancy, due to complicated physical, emotional and hormonal changes taking place.
Anti-Seizure Medication and Children
Anti-seizure information is usually not recorded the first time a child has a seizure because approximately 50% of them will never have another. When a second seizure occurs the chances of having another seizure increases to 80%. For this reason, it is important that the family and physician discuss using anti-seizure medication to prevent further seizures. Families need to find a proper balance between the uncertainty of recurrent seizures and their associated risks, and the possibility of side effects from the medication. If a child is started on medication, it is usually continued for one to two years after seizures have stopped. Approximately 20% of children on medication never have another seizure. Another 20% of children on medication never have difficulty in controlling the seizures that last throughout childhood. It is thought, that for the remaining 60% of children, half will be seizure free after only a year or two, and the remainder will have a tough time for several years before seizures stop or are under adequate control.
Since children grow rapidly, regular checkups are important. Children may outgrow their medication dosage; thus, an increase may be needed. The dosage may need to be adjusted at the onset of puberty. For pre-adolescents and adolescents who are on long term anti-seizure medication, calcium supplements may be recommended. In addition, parents or guardians need to make sure that a medication is being taken as prescribed. If medication needs to be taken during school hours, talk to your child, physician, and the school about how to handle this.
Seniors and Medications
If you are a senior citizen, you may remember a time when treatment for epilepsy was very limited. For many years, epilepsy was viewed as a condition of childhood. We now know that, although epilepsy often does begin in the first decade of life, people are even more likely to have this disorder in their sixties or seventies. Today, epilepsy is a well-understood neurological condition; it is not contagious, and is not a mental illness. There are many medications that can be successfully used in the treatment of seizures. Many seniors with seizures can lead active, productive lives. The majority of the advice in this pamphlet is useful for seniors, but the following points may be especially beneficial for seniors:
- You may be more sensitive to medication side effects, such as unsteadiness, fatigue, changed behaviour, and confusion.
- If you are taking other medications such as blood pressure pills, blood thinners, drugs to reduce cholesterol, etc., they may interact with your anti-seizure drugs. Therefore, it is very important to tell your physician or pharmacist about any other medications you are taking.
- Keep a record of your seizures, it is very helpful when you visit your physician.
- Wear a MedicAlert TM or similar bracelet.
Common AEDs By Seizure Type
Absence Seizures
Complex Partial Seizures
Lennox-Gastaut Syndrome
Myoclonic Seizures
Photosensitive Seizures
Simple Partial Seizures
Status Epilepticus
Tonic-Clonic Seizures
West's Syndrome
The support of Epilepsy Canada (use of print and photographs of medication), Epilepsy London & Area, Dr. M. Burnham and HRDC (Human Resource Development Canada) Summer Career Placement Program is acknowledged. Thanks to Theresa Sargeson for her work in researching and creating this project.
