Ethosuximide

Ethosuximide is an anticonvulsant medicine. It works by binding with the T-type voltage sensitive calcium channels to regulate the entrance for calcium ions in the nerves and brain. In this way, it decreases the hyperactivity of the brain and nerves. Thus, it works on the nervous system to treat seizures (fits).

Ethosuximide is used mainly in the management of absence (petite mal) seizures. It is usually ineffective in the management of partial seizures with complex symptomatology or tonic-clonic seizures.

• Absence Seizures: Indicated for the control of absence (petit mal) seizures.

Primary anti-epileptic drugs

Anticonvulsant (Succinimide)

Ethosuximide suppresses the paroxysmal three cycle per second spike and wave activity associated with lapses of consciousness which is common in absence (petit mal) seizures. The frequency of epileptiform attacks is reduced, apparently by depression of the motor cortex and elevation of the threshold of the central nervous system to convulsive stimuli.

Ethosuximide blocks T-type calcium channels, reducing neuronal hyperexcitability and helping to control seizures.

Adult Dose (Oral):

• Initial: 500 mg daily (single or divided doses)
• Increase: 250 mg every 4-7 days
• Usual dose: 1-1.5 g daily
• Max: Up to 2 g in some patients
• Optimum plasma concentration: 40-100 mg/L

Child Dose (3-6 years): Initial: 5 mL (250 mg)/day; increase by 5 mL (250 mg) every 4-7 days; usual maintenance: 20 mg/kg or 1.2 g/m²/day.

Child Dose (>=6 years): Initial: 10 mL (500 mg)/day; increase by 5 mL (250 mg) every 4-7 days.

Take this medicine in the dose and duration as advised by your doctor. Check the label for directions before use. Measure it with a measuring cup and take it by mouth. Shake well before use. Ethosuximide may be taken with or without food, but it is better to take it at a fixed time.

If you miss a dose, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular schedule. Do not double the dose.

Common Side Effects:

• Nausea
• Vomiting
• Fatigue
• Indigestion
• Stomach pain
• Dizziness
• Lightheadedness
• Diarrhea
• Weight loss
• Headache
• Loss of appetite
• Hiccup
• Ataxia
• Irritability, aggression

Rare Side Effects: Tongue swelling, sleep disturbances, depression, psychosis, photophobia, dyskinesia, vaginal bleeding, myopia, gingival hypertrophy, rash, blood disorders (leucopenia, agranulocytosis, pancytopenia, aplastic anaemia), SLE, Stevens-Johnson syndrome.

Precautions:

• Ethosuximide may affect your ability to drive; do not drive until you know how it affects you.
• Take it only as per dose and duration prescribed by your doctor.
• It may cause dizziness; do not do anything that requires mental focus.
• Your doctor may get regular tests done to monitor kidney function, liver function, and blood cell levels.
• Inform your doctor if you notice changes in mood, behavior or if you have suicidal thoughts.
• Inform your doctor if you are pregnant, planning pregnancy or breastfeeding.
• Do not stop taking medication suddenly without talking to your doctor (can worsen seizures).

Contraindications:

• Hypersensitivity to succinimides
• Pregnancy and lactation

Drug Interactions:

• Isoniazid: May increase serum concentration of ethosuximide (leading to toxicity).
• Antipsychotics, antidepressants, MAOIs, mefloquine: May antagonize anticonvulsant effects.
• Carbamazepine, phenobarbital, phenytoin, primidone: May reduce plasma concentration of ethosuximide.
• Valproate: May affect levels.
• Chloroquine or hydroxychloroquine: May increase risk of convulsions.

Food Interactions: No data available; consult your doctor.

Use in Pregnancy: Ethosuximide may be unsafe; animal studies have shown harmful effects on the developing baby.

Use in Lactation: Probably safe; limited human data suggests no significant risk to the baby.

Pediatric Use: Dosage established for children 3 years and older.

Geriatric Use: No specific dosage adjustment is necessary for elderly patients.

Renal Impairment: Limited information available; use with caution.

Hepatic Impairment: Limited information available; use with caution.

Overdose: Acute overdoses may produce nausea, vomiting and CNS depression including coma.

Storage: Store in a cool and dry place protected from light. Keep out of reach of children.

Ethosuximide