Ethosuximide
Administration
- Type: Anticonvulsant
- Dosage Forms: 250; 250/5mL
- Routes of Administration: oral tablet, oral syrup
- Common Trade Names: Zarontin
Adult Dosing
Seizure, absence
- Start: 250mg PO bid
- May increase 250mg/day q4-7 days
- Taper dose based on tx response to D/C
- Max: 1.5 g/day
Pediatric Dosing
Seizure, absence
- 3-6 yo
- 20 mg/kg/day PO divided bid
- Start: 250 mg PO QD
- Max: 1.5 g/day
- Taper dose based on tx response to D/C
- 20 mg/kg/day PO divided bid
- 6+ yo
- 20 mg/kg/day PO divided bid
- Start: 250 mg PO QD
- Max: 1.5 g/day
- Taper dose based on tx response to D/C
- 20 mg/kg/day PO divided bid
Special Populations
- Pregnancy Rating: C
- Lactation risk: L3
Renal Dosing
- Adult:
- CrCl <10: Decrease dose 25%
- HD: Give after dialysis
- PD: No adjustment
- Pediatric:
- CrCl <10: Decrease dose 25%
- HD: Give after dialysis
- PD: No adjustment
Hepatic Dosing
- Adult: Not defined
- Pediatric: Not defined
Contraindications
- Allergy to class/drug
Adverse Reactions
Serious
- Agranulocytosis
- Pancytopenia
- Leukopenia
- Blood dyscrasias
- Lupus erythematosus
- Aggressive behavior
- Suicidality
- Depression
- Paranoid psychosis
- Stevens-Johnson syndrome
- Hypersensitivity reaction
- Withdrawal seizures if abrupt D/C
Common
- Anorexia
- Dyspepsia
- Nausea/Vomiting
- Abdominal pain
- Weight loss
- Diarrhea
- Drowsiness
- Headache
- Dizziness
- Euphoria
- Hiccups
- Irritability
- Hyperactivity
- Ataxia
- Sleep disturbance
- Impaired concentration
- Rash
- Pruritus
- Hirsutism
Pharmacology
- Half-life: 56-60 hr
- Metabolism: Liver extensively; CYP450: 3A4 substrate
- Excretion: Urine primarily (<20% unchanged), bile/feces
Mechanism of Action
- Depresses motor cortex
- Elevates CNS convulsive stimuli threshold