Last reviewed 2026-04-20 · How we verify

Zarontin (ETHOSUXIMIDE)

Zarontin (ETHOSUXIMIDE) is a small molecule anti-epileptic agent developed by Parke Davis, currently owned by the same company. It targets the voltage-dependent T-type calcium channel subunit alpha-1G, modulating neuronal excitability. Zarontin is FDA-approved for the treatment of absence seizures and is available as a generic medication. The drug has a high bioavailability of 93% and is off-patent, with multiple generic manufacturers. As an off-patent medication, Zarontin's commercial status is primarily driven by generic competition.

At a glance

Approved indications

• Absence seizure

Common side effects

• Gastrointestinal symptoms
• Anorexia
• Vague gastric upset
• Nausea
• Vomiting
• Cramps
• Epigastric and abdominal pain
• Weight loss
• Diarrhea
• Gum hypertrophy
• Swelling of the tongue
• Leukopenia

Drug interactions

• phenytoin
• valproic acid

Key clinical trials

• Population Pharmacokinetics of Antiepileptic in Pediatrics
• Ketogenic Diet for New-Onset Absence Epilepsy (PHASE3)
• Investigate the Clinical Responses of Ethosuximide in Patients With Treatment-Resistant Depression. (EARLY_PHASE1)
• Ethosuximide to Treat IBS (PHASE2)
• Evaluation of the Efficacy and Tolerance of Low Doses of Ethosuximide in the Treatment of Peripheral Neuropathic Pain (PHASE2)
• Childhood Absence Epilepsy Rx PK-PD-Pharmacogenetics Study (PHASE3)
• Ethosuximide and Pentoxifylline in the Treatment of Abdominal Pain Related to Irritable Bowel Syndrome (PHASE3)
• Assessment of the Effectiveness of Ethosuximide in the Treatment of Peripheral Neuropathic Pain. (PHASE2)

Primary sources

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