Antiepileptic Drugs Health Article

Withdrawal

Treatment is normally continued for a minimum of two years after the last seizure. Withdrawal should be extended over a period of several months, as abrupt withdrawal can lead to complications such as status epilepticus, a serious event where seizures occur rapidly and continuously. Many adult patients relapse once treatment is withdrawn and it may be justified to continue treatment indefinitely, particularly when the patient's livelihood or lifestyle can be endangered by recurrence of a seizure.

Pregnancy and Breast-feeding

Untreated epilepsy during pregnancy may cause harm to the fetus; there is, therefore, no justification for abrupt withdrawal of treatment. Withdrawal of therapy with antiepileptic medications may be an option if the patient has been seizure-free for at least two years. Resumption of treatment may be considered after the first trimester. If antiepileptics are continued in pregnancy, a single medication with the lowest effective dose is preferred, and blood levels of the medication should be monitored. There is an increased risk of birth defects with the use of AEDs, particularly carbamazepine, valproate, and phenytoin. However, if there is good seizure control, many physicians see no advantage in changing pregnant patients' AEDs. In view of the risks of neural tube and other defects, patients who may become pregnant should be informed of the risks and referred for advice, and pregnant patients should be offered counseling and screening. To counteract the risk of neural tube defects, adequate folic acid supplements are advised for women before and during pregnancy. In view of the risk of bleeding associated with carbamazepine, phenobarbital, and phenytoin, prophylactic phytomenadione (vitamin K1) is recommended for the mother before delivery and the newborn. Use of AEDs can often be continued during breastfeeding.

Driving

Regulations are in place in many countries that may restrict driving by patients with epilepsy. Further, AEDs may cause central nervous system depression, particularly in the early stages of treatment. Patients affected by adverse effects such as drowsiness or dizziness should not operate machinery or drive.

Side effects

The most common side effects of therapy with antiepileptic drugs are drowsiness and dizziness. Other drug-specific side effects include:

• Carbamazepine: Dizziness, double vision, nausea, loss of coordination, and blurred vision.
• Clonazepam: Sedation, ataxia (loss of coordination), hyperactivity, restlessness, irritability, depression, cardiovascular or respiratory depression. Children and infants may have excess saliva production. Occasionally, tonic seizures may be exacerbated.
• Diazepam: Drowsiness, dizziness, tiredness, weakness, dry mouth, diarrhea, upset stomach, changes in appetite, restlessness or excitement, constipation, difficulty urinating, frequent urination, blurred vision, changes in sex drive or ability.
• Ethosuximide: Drowsiness, upset stomach, vomiting, constipation, diarrhea, stomach pain, loss of taste and appetite, weight loss, irritability, mental confusion, depression, insomnia, nervousness, and headache.
• Felbamate: Insomnia, weight loss, nausea, decreased appetite, dizziness, fatigue, ataxia (loss of coordination), and lethargy.
• Fosphenytoin: Burning/tingling sensations, groin pain, itching, nausea, dizziness or drowsiness may occur. Serious side effects may occur: mental/mood changes, loss of coordination, rash, eye/vision problems.
• Lamotrigine: Rash is the main concern associated with this drug. Other commonly reported adverse reactions are headache, blood dyscrasias, ataxia (loss of coordination), double vision, psychosis, tremor, hypersensitivity reactions, and prolonged sleepiness or insomnia.
• Levetiracetam: Sleepiness, asthenia (loss of strength), dizziness, accidental injury, convulsion, infection, pain, pharyngitis, and a flu-like syndrome.
• Oxcarbazepine: Sleepiness, headache, dizziness, rash, low blood sodium level, weight gain, and hair loss.
• Phenobarbital: Thought and behavior alterations, sedation, psychomotor slowing, poor concentration, depression, irritability, ataxia (loss of coordination), and decreased libido.
• Phenytoin sodium: Ataxia (loss of coordination), abnormal rapid eye movements, drowsiness and lethargy, nausea and vomiting, rash, blood disorders, headaches, vitamin K and folate deficiencies, loss of libido, hormonal dysfunction, and bone marrow suppression.
• Primidone: Intense sedation, dizziness, and nausea at the onset of treatment.
• Sodium valproate: Nausea, vomiting, tremor, sedation, confusion or irritability, and weight gain, elevated blood sugar levels, and hair loss or curling of hair.
• Tiagabine: Dizziness, fatigue, depression, confusion, impaired concentration, speech or language problems, lack of energy, weakness, upset stomach, nervousness, tremor, and stomach pain.
• Topiramate: Dizziness, sleepiness, ataxia (loss of coordination), confusion, fatigue, decreased sensation in lower extremities, speech difficulties, double vision, impaired concentration, and nausea.
• Zonizamide: Dizziness, anorexia, headache, ataxia (loss of coordination), confusion, speech abnormalities, mental slowing, irritability, tremor, weight gain, excessive sleepiness, and fatigue.