Ethosuximide
ZARONTIN
What it isT-type calcium-channel blocker in thalamic neurons; absence seizures.
Why this oneIt is first-line for childhood absence epilepsy and preserves attention better than valproate.
What limits itIt does not cover tonic-clonic seizures; GI intolerance is common, and rare blood dyscrasias require counts.
FDA-approved for
- absence seizures (~1960)
FDA label
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| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Absence (petit mal) seizures | 3-6 years | 250 mg QD | ~20 mg/kg/day | 1.5 g/day (divided) |
| Absence (petit mal) seizures | >=6 years / adult | 500 mg QD | individualized | 1.5 g/day (divided) |
Titration Increase by 250 mg every 4-7 days until control achieved
Renal Undefined
Hepatic Undefined
Instructions
- Oral
- Give higher doses (>1.5 g/day) in divided doses only under strict supervision
- May combine with other anticonvulsants if mixed seizure types coexist
Cautions
- Blood dyscrasias (leukopenia, agranulocytosis, pancytopenia) — monitor CBC
- DRESS / multiorgan hypersensitivity
- Stevens-Johnson syndrome
- Psychiatric disturbances incl. depression and suicidal ideation
Adverse reactions
- GI: anorexia, nausea, vomiting, cramps, abdominal pain, weight loss
- Drowsiness, headache, dizziness, ataxia, hiccups
- Blood dyscrasias
- DRESS, SJS, urticaria
- Sleep disturbance, night terrors, aggressiveness
Pregnancy Undefined
Lactation Undefined
NO BOXED WARNINGS
Principal riskIt does not cover tonic-clonic seizures; blood dyscrasias
Cost, est. cash$10–$300/month
Generic entry1993
Classes and tags
Clinical profile
Legacy pregnancy categoryC
Defining liabilitySedation, dizziness and agent-specific rash, behavioral, hepatic, hematologic or teratogenic toxicity.
Mechanism of action: Ethosuximide ballicule
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Memory aids: mascots and interaction avatars
Child with petit mal seizure (approved for age 3+)
Drug of choice for absence seizures
