Indications
Ethosuximide is an anti-epileptic medicine used mainly to control absence seizures (petit mal), brief episodes, usually in children, where the person stares blankly and loses awareness for a few seconds. It may also be used for myoclonic seizures in some cases. It does not protect against tonic-clonic (grand mal) seizures, so another medicine is added if those also occur.
How It Works
Absence seizures are linked to abnormal rhythmic electrical activity between the thalamus and the outer layer of the brain. Ethosuximide blocks a type of calcium channel (T-type calcium channels) in thalamic nerve cells, which calms this rhythm and prevents the seizures.
Dosage and Administration
Take exactly as prescribed. The dose is started low and increased slowly every few days until seizures are controlled, and it is based on age and body weight in children, so your doctor will set the right amount. It is available as capsules and syrup and can be taken with food to reduce stomach upset. Use the measuring device supplied for the syrup. Do not stop suddenly, because this can bring on seizures; your doctor will reduce the dose gradually if needed.
Interactions
- Carbamazepine, Phenytoin, Phenobarbital and Primidone may lower Ethosuximide levels.
- Valproate (Valproic Acid) and Isoniazid may raise Ethosuximide levels.
- Ethosuximide may change Phenytoin levels.
- Alcohol and other sedating medicines can add to drowsiness.
- Antidepressants and antipsychotics may lower the seizure threshold.
Contraindications
- Allergy to Ethosuximide or other succinimide anticonvulsants.
Side Effects
Common side effects include nausea, vomiting, stomach pain, loss of appetite, hiccups, drowsiness, dizziness, headache and tiredness. Behaviour changes, sleep problems and difficulty concentrating can occur.
Rare but serious effects include blood disorders (low white cells or platelets), lupus-like illness, serious skin reactions, and mood changes or suicidal thoughts.
Get urgent medical help if there is fever, sore throat, mouth ulcers, unusual bruising or bleeding, a widespread rash with blisters or peeling, joint pain with rash, a sharp increase in seizures, or thoughts of self-harm.
Pregnancy and Lactation
Ethosuximide crosses the placenta. Uncontrolled seizures are also risky in pregnancy, so do not stop treatment on your own; speak to your doctor before or as soon as you become pregnant, and folic acid is usually advised. It passes into breast milk in large amounts; if breastfeeding, watch the baby for drowsiness or poor feeding and follow your doctor’s advice.
Precautions and Warnings
- Regular blood counts and sometimes liver and kidney tests are needed.
- Use with care in liver or kidney disease.
- It may cause drowsiness; avoid driving or dangerous activities until you know how it affects you.
- Family members should watch for changes in mood or behaviour.
- Report signs of infection such as fever or sore throat promptly.
Overdose
Overdose may cause severe drowsiness, nausea, vomiting, slow breathing and coma. Seek emergency medical care immediately. Treatment is supportive in hospital.
Therapeutic Class
Anticonvulsant, succinimide.
Storage
Store below 30°C in a dry place, away from light and out of the reach of children. Do not freeze the syrup.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.