ETHOSUXIMIDE

Mechanism of Action :

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.

Indication, Dosage and Frequency :

Oral
ABSENCE SEIZURES
Adult: Initially, 500 mg daily, may increase in steps of 250 mg at intervals of 4-7 days. Usual dose: 1-1.5 g daily. Optimum plasma concentration: 40-100 mg/L (300-700 micromol/L). Max: Up to 2 g in some patients. Strict supervision is recommended if dose >1.5 g daily.
Child: <6 yr: Initially, 250 mg daily, may increase gradually to usual dose of 20 mg/kg daily. ≥6 yr: Initially, 500 mg daily, may increase in steps of 250 mg at intervals of 4-7 days. Usual dose: 1-1.5 g daily. Max: <6 yr: Up to 1 g/day and ≥6 yr: 2 g/day .

Interactions :

Isoniazid may increase the serum concentration of ethosuximide, leading to toxicity. Antipsychotics, antidepressants, MAOIs, and mefloquine may antagonise anticonvulsant effects of ethosuximide. Plasma conc of ethosuximide may be reduced by carbamazepine, phenobarbital, phenytoin, and primidone; and affected by valproate. Chloroquine or hydroxychloroquine may increase risk of convulsions.