Ethosuximide Dosage

Medically reviewed by Drugs.com. Last updated on Jul 15, 2024.

Applies to the following strengths: 250 mg; 250 mg/5 mL

Usual Adult Dose for Seizures

Initial dose: 500 mg orally once a day

Increase dose in small increments, for example 250 mg daily every 4 to 7 days, until optimal seizure control with minimal side effects is achieved

Maintenance dose: Individualized; generally, a dose that provides efficacy and tolerability with a plasma level within the accepted therapeutic range (40 to 100 mcg/mL)

Comments:

Doses exceeding 1.5 g per day should be administered only under strict supervision of a physician.
For higher daily doses, consider twice a day dosing.
This drug may be administered in combination with other anticonvulsants when other forms of epilepsy coexist.

Use: For the control of absence (petit mal) seizures.

Usual Pediatric Dose for Seizures

3 to 6 years old:
Initial dose: 250 mg orally once a day

6 years or older:
Initial dose: 500 mg orally once a day

Titration: Increase dose in small increments, for example 250 mg daily every 4 to 7 days, until optimal seizure control with minimal side effects is achieved
Maintenance dose: Individualized; generally, a dose that provides efficacy and tolerability with a plasma level within the accepted therapeutic range (40 to 100 mcg/mL)
Optimal dose for most pediatric patients: 20 mg/kg/day; some authorities have found doses up to 40 mg/kg/24 hours are needed to obtain therapeutic levels

Comments:

Doses exceeding 1.5 g per day should be administered only under strict supervision of a physician.
For higher daily doses, consider twice a day dosing.
This drug may be administered in combination with other anticonvulsants when other forms of epilepsy coexist.

Use: For the control of absence (petit mal) seizures.

Renal Dose Adjustments

Renal disease: Administer with extreme caution

Liver Dose Adjustments

Liver disease: Administer with extreme caution

Dose Adjustments

Therapeutic blood level monitoring:

Accepted therapeutic range: 40 to 100 mcg/mL

Concomitant Use with other Antiepileptic Drugs

Periodic serum level determinations of antiepileptic drugs may be necessary
This drug may elevate phenytoin serum levels
Valproic acid may both increase and decrease ethosuximide levels

Changes to Dosing Regimen:

Dose changes, as well as, the addition and/or elimination of other antiepileptic medications should be done slowly; avoid abrupt withdrawal

Precautions

NARROW THERAPEUTIC INDEX:

This drug should be considered a narrow therapeutic index (NTI) drug as small differences in dose or blood concentrations may lead to serious therapeutic failures or adverse drug reactions.

Recommendations:

Generic substitution should be done cautiously, if at all, as current bioequivalence standards are generally insufficient for NTI drugs.
Additional and/or more frequent monitoring should be done to ensure receipt of an effective dose while avoiding unnecessary toxicities.

CONTRAINDICATIONS:

Hypersensitivity to succinimides

Safety and efficacy have not been established in patients younger than 3 years.

Consult WARNINGS section for additional precautions.

Dialysis

Data not available

Other Comments

Administration advice:

Take orally
An adequately calibrated measuring device such as an oral syringe, should be used to measure liquid doses

Storage requirements:

Oral solution: Protect from freezing and light

General:

Using this drug as monotherapy in patients with mixed type of epilepsy may increase the frequency of grand mal seizures in some patients.
Abrupt withdrawal may precipitate seizures; as with other antiepileptic drugs, dose increases and decreases should proceed slowly.

Monitoring:

Blood counts, periodically, and if signs and/or symptoms of infection develop
Urinalysis periodically
Liver function tests periodically
Monitor for the emergence or worsening of depression, suicidal thoughts or behavior, and/or any unusual changes in mood or behavior
Monitor for rash

Patient advice:

Read the US FDA-approved patient labeling (Patient Information).
Patients should understand the importance of strictly adhering to their dosing regimen.
Patients should be appropriately counseled regarding the performance of potentially hazardous tasks.
Patients should be instructed to contact their healthcare provider promptly if they develop a rash or signs and symptoms of an infection.
Patients and/or caregivers should monitor for the emergence or worsening of depression, suicidal thoughts or behavior, and/or any unusual changes in mood or behavior; behaviors of concern should be reported promptly.
Women of childbearing potential should speak with their physician if they are or intend to become pregnant, or are breastfeeding.