Ethosuximide

Ethosuximide is indicated for the control of absence seizures.

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.

Pediatric Patients-

• Children 3 to 6 years of age: Initially 5 ml (250 mg) daily in a single dose
• Children ≥6 years of age: Initially 10 ml (500 mg) daily in a single dose or divided doses
• Dosage should be increased by small increments, by 5 ml (250 mg) every 4–7 days until seizure control is achieved with minimal adverse effects. Dosage usually should not be >30 ml (1.5 g) daily, given in divided doses. If dosage is >1.5 g daily, clinical must closely supervise patients.
• Usual maintenance dosage: 20 mg/kg or 1.2 g/m2 daily

Adults-

• Initially 10 ml (500 mg) daily in a single dose or divided doses
• Dosage should be increased by small increments, by 5 ml (250 mg) every 4–7 days until seizure control is achieved with minimal adverse effects. Dosage usually should not be >30 ml (1.5 g), given in divided doses.
• Usual maintenance dosage: 20 mg/kg or 1.2 g/m2 daily

The plasma concentrations of ethosuximide may be reduced by carbamazepine, primidone, phenobarbitone and lamotrigine and increased by isoniazid. No consistent changes in levels of ethosuximide occur when used in combination with phenytoin or sodium valproate. Phenytoin levels however are increased by concomitant ethosuximide.

Ethosuximide should not be used in patients with hypersensitivity to succinimides (e.g. methosuximide, phenosuximide) & known hypersensitivity to the active substance or to any of the excipients.

The common side effects of ethosuximide are gastro-intestinal disturbances including nausea, vomiting, diarrhoea, abdominal pain, anorexia, weight loss. The less frequent side effects are headache, fatigue, drowsiness, dizziness, hiccup, ataxia, mild euphoria, irritability, aggression, impaired concentration; rarely tongue swelling, sleep disturbances, night terrors, depression, psychosis, photophobia, dyskinesia, increased libido, vaginal bleeding, myopia, gingival hypertrophy, and rash; hyperactivity, increase in seizure frequency, blood disorders such as leucopenia, agranulocytosis, pancytopenia, and aplastic anaemia, systemic lupus erythematosus, and Stevens-Johnson syndrome.

Ethosuximide crosses the placenta. Risk-benefit ratio should be weighed in treating or counseling epileptic women of childbearing potential. Ethosuximide is excreted in breast milk. It should be used in nursing mothers only if the benefits clearly outweigh the risks. Breast feeding is best avoided.

Ethosuximide should be used with caution in hepatic or renal impairment. Ethosuximide may impair the mental and/or physical abilities required for the performance of potentially hazardous tasks such as driving or other such activities requiring alertness. Therefore, the patient should be cautioned accordingly. Abrupt withdrawal should be avoided. Patients should be monitored for signs of suicidal ideation & behaviors and appropriate treatment should be considered.

Acute overdoses may produce nausea, vomiting and CNS depression including coma with respiratory depression. Relationship between ethosuximide toxicity and its plasma levels has not been established.

Primary anti-epileptic drugs

Keep away from the reach of children. Store in a cool and dry place protected from light.