II. Indications

III. Mechanism

  1. Succinimide anticonvulsant
  2. Partial Antagonist of T-type Calcium channels within thalamic Neurons
  3. Decreases burst firing of thalamocortical Neurons, stabilizing CNS nerve activity

IV. Dosing: Absence Seizures

  1. Therapeutic level: 40 to 100 mcg/ml
  2. Adults (and children age >6 years old)
    1. Start 500 mg orally once daily
    2. May increase dose by 250 mg/day every 4 to 7 days
    3. Maximum: 1.5 grams/day
  3. Children (ages 3 to 6 years old)
    1. Start 250 mg orally once daily
    2. May increase dose by 250 mg/day every 4 to 7 days
    3. Target dose: 20 mg/kg/day
  4. Renal Dosing (CrCl <10 ml/min)
    1. Reduce dose 25%

V. Safety

  1. Pregnancy Category C
  2. Considered Safe in Lactation
  3. Monitor Complete Blood Count (cbc), and periodic Urinalysis and Liver Function Tests

VI. Metabolism

  1. Hepatic metabolism
  2. Highly Protein bound
  3. Half Life increased in liver disease and in children

VII. Adverse Effects

  1. Dose dependent effects (decreases overtime with use, and with divided dosing)
    1. Nausea or Vomiting
    2. Decreased appetite (with weight loss)
    3. Sedation
  2. Serious
    1. Neutropenia (rare)
      1. Mild Leukopenia, however, is common
    2. Increased Generalized Tonic Clonic Seizures

VIII. Drug Interactions

  1. Valproic Acid
    1. Valproic Acid increases Ethosuximide levels
    2. Ethosuximide decreases valproic levels
  2. Phenytoin
    1. Ethosuximide increases Phenytoin levels
  3. Primidone
    1. Ethosuximide decreases Primidone levels

X. References

  1. (2022) Presc Lett, Resource #361206, Antiseizure Medications
  2. Olson (2020) Clinical Pharmacology, Medmaster Miami, p. 56-7
  3. Hamilton (2020) Tarascon Pocket Pharmacopoeia

Images: Related links to external sites (from Bing)

Related Studies

Cost: Medications

ethosuximide (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
ETHOSUXIMIDE 250 MG CAPSULE Generic $0.40 each
ETHOSUXIMIDE 250 MG/5 ML SOLN Generic $0.09 per ml

Ontology: Ethosuximide (C0015043)

Definition (NCI) A succinimide with anticonvulsant activity. The exact mechanism of action is not entirely understood, but most likely ethosuximide exerts its effects by partial antagonism of T-type calcium channels of the thalamic neurons. This leads to a decrease in burst firing of thalamocortical neurons, which stabilizes the nerve activity in the brain and prevents seizures.
Definition (MSH) An anticonvulsant especially useful in the treatment of absence seizures unaccompanied by other types of seizures.
Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH D005013
SnomedCT 322899006, 387244008, 44790008
LNC LP16137-9, MTHU004937
English Ethosuximide, Ethosuccimid, Ethylmethylsuccimide, ethosuximide, 2,5-Pyrrolidinedione, 3-ethyl-3-methyl-, 3-Ethyl-3-methylpyrrolidine-2,5-dione, ethosuximide (medication), ETHOSUXIMIDE, Ethosuximide [Chemical/Ingredient], Ethosuximide (product), Ethosuximide (substance)
Swedish Etosuximid
Czech ethosuximid
Finnish Etosuksimidi
Italian Etosuccimide, Etil-metil-succimide, Etosuximide
Russian ETOSUKTSIMID, ETOSUKSIMID, ЭТОСУКСИМИД, ЭТОСУКЦИМИД
Polish Etosukcynimid, Ronton, Zarontyna
Japanese エトスクシミド, エトサクシミド
Spanish etosuximida (producto), etosuximida (sustancia), etosuximida, Etosuximida, Etosuccimida
French Éthosuximide
German Ethosuccimid, Ethosuximid
Portuguese Etossuccimida, Etossuximida