Ethosuximide

Indications

Ethosuximide is used for: Absence seizures

Adult Dose

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. Hepatic Impairment Monitor closely

Child Dose

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 .

Renal Dose

Renal Impairment Monitor closely

Administration

May be taken with or without food.

Contra Indications

Hypersensitivity. Pregnancy and lactation.

Precautions

Hepatic or renal impairment, porphyria. Complete blood cell count, liver function tests, and urinalysis should be performed periodically. May increase the risk of grand mal seizures when used alone in mixed types of epilepsy. Avoid sudden withdrawal. May impair ability to drive or operate machinery. Lactation: enters breast milk; use with caution (AAP Committee states "compatible with nursing")

Pregnancy-Lactation

Pregnancy Category: C Lactation: enters breast milk; use with caution (AAP Committee states "compatible with nursing")

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. Isoniazid.

Adverse Effects

Side effects of Ethosuximide : Common Dizziness, Headache, Somnolence, Anorexia, Diarrhea, GI upset, Nausea, Vomiting Less Common Ataxia, confusion, drowsiness, sleep disturbance, Gum hypertrophy, hiccoughs, swelling of tongue, Blood dyscrasias including aplastic anemia, Allergic reaction, Urticaria, Pruritic erythematous rashes, Blurred vision, myopia Rare Psychosis, Seizure, Suicidal thoughts and behavior, Stevens-Johnson syndrome, Systemic lupus erythematosus, Hirsutism

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.