ethosuximide (Rx)

Brand and Other Names:Zarontin
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Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

capsule

  • 250mg

syrup

  • 250mg/5mL
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Absence Seizures

500 PO qDay, increase by 250 mg q4-7d; generally not to exceed 1.5 g/day

Therapeutic range: 40-100 mg/L (may require 4-7 days to reach steady-state)

Dosage Modifications

Renal or hepatic impairment: Monitor closely

Dosage Forms & Strengths

capsule

  • 250mg

syrup

  • 250mg/5mL
more...

Absence Seizures

<3 years: Safety and efficacy not established

3-6 years: 250 mg PO qDay initially; if needed, may increase by 250 mg q4-7d; usual maintenance dose 20 mg/kg/day  

>6 years: As adults, 500 mg PO qDay initially; may increase by 250 mg q4-7d; generally not to exceed 1.5 g/day in divided doses

Therapeutic range: 40-100 mg/L (may require 4-7 days to reach steady state)

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Interactions

Interaction Checker

and ethosuximide

No Results

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    No Interactions Found
    Interactions Found

    Contraindicated

      Serious - Use Alternative

        Significant - Monitor Closely

          Minor

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            Adverse Effects

            Freqency Not Defined

            Common

            • Dizziness
            • Headache
            • Somnolence
            • Anorexia
            • Diarrhea
            • GI upset
            • Nausea
            • Vomiting

            Less Common

            • Ataxia, confusion, drowsiness, sleep disturbance
            • Gum hypertrophy, hiccoughs, swelling of tongue
            • Blood dyscrasias including aplastic anemia
            • Allergic reaction
            • Urticaria
            • Pruritic erythematous rashes
            • Blurred vision, myopia

            Rare

            • Psychosis
            • Seizure
            • Suicidal thoughts and behavior
            • Stevens-Johnson syndrome
            • Systemic lupus erythematosus
            • Hirsutism
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            Warnings

            Contraindications

            Hypersensitivity

            Cautions

            Do not discontinue rapidly; proceed slowly when increasing or decreasing dosage, as well as when adding or eliminating other medications; abrupt withdrawal of anticonvulsant medication may precipitate absence (petit mal) status

            When used alone in mixed types of epilepsy, therapy may increase frequency of grand mal seizures in some patients

            Blood dyscrasias may occur; perform periodic blood counts; should signs and/or symptoms of infection (e.g., sore throat, fever) develop, consider blood counts

            Systemic lupus erythematosus reported

            May cause CNS depression

            Antiepileptic drugs increase risk of suicidal thoughts or behavior in patients taking these drugs for any indication; monitor for the emergence or worsening of depression, suicidal thoughts or behavior, and/or any unusual changes in mood or behavior

            May potentiate effect of other sedatives

            Serious dermatologic reactions reported including Stevens Johnson syndrome (SJS); onset usually within 28 days, but can occur later; discontinue therapy at first sign of rash, unless rash is clearly not drug-related; if signs or symptoms suggest SJS, use of this drug should not be resumed; consider alternative therapy

            Drug reaction with Eosinophilia and Systemic Symptoms (DRESS), also known as multi organ hypersensitivity, reported; some fatal or life-threatening; early manifestations of hypersensitivity (e.g. fever, lymphadenopathy) may be present even though rash is not evident; if such signs or symptoms appear, the patient should be evaluated immediately and therapy discontinued if an alternative etiology for the signs or symptoms cannot be established

            Abnormal renal and hepatic function studies reported; administer with extreme caution to patients with known liver or renal disease; periodic urinalysis and liver function studies recommended for all patients receiving the drug

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            Pregnancy & Lactation

            Pregnancy Category: C

            Lactation: enters breast milk; use with caution (AAP Committee states "compatible with nursing")

            Pregnancy Registry: Pregnant women exposed to ethosuximide are encouraged to enroll themselves by calling 1-888-233-2334.

            Pregnancy Categories

            A:Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

            B:May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

            C:Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

            D:Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

            X:Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

            NA:Information not available.

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            Pharmacology

            Mechanism of Action

            Succinimide; depresses nerve transmission in motor cortex, increases convulsive stimuli threshold in CNS

            Pharmacokinetics

            Peak Plasma Time: 4 hr

            Protein bound: Low

            Metabolism: liver (hydroxylation, glucuronidation)

            Excretion: Mainly renal, some bile

            Half-life

            • Children: 30 hr
            • Adults: 60 hr
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            Administration

            Oral Administration

            May take with food or milk

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            Images

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            Formulary

            FormularyPatient Discounts

            Adding plans allows you to compare formulary status to other drugs in the same class.

            To view formulary information first create a list of plans. Your list will be saved and can be edited at any time.

            Adding plans allows you to:

            • View the formulary and any restrictions for each plan.
            • Manage and view all your plans together – even plans in different states.
            • Compare formulary status to other drugs in the same class.
            • Access your plan list on any device – mobile or desktop.

            The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

            Tier Description
            1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
            2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
            3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
            4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            NC NOT COVERED – Drugs that are not covered by the plan.
            Code Definition
            PA Prior Authorization
            Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
            QL Quantity Limits
            Drugs that have quantity limits associated with each prescription. This restriction typically limits the quantity of the drug that will be covered.
            ST Step Therapy
            Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
            OR Other Restrictions
            Drugs that have restrictions other than prior authorization, quantity limits, and step therapy associated with each prescription.
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