ethosuximide (Rx)

Brand and Other Names:Zarontin
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Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

capsule

  • 250mg

syrup

  • 250mg/5mL

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

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

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              Serious - Use Alternative (23)

              • abametapir

                abametapir will increase the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. For 2 weeks after abametapir application, avoid taking drugs that are CYP3A4 substrates. If not feasible, avoid use of abametapir.

              • apalutamide

                apalutamide will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of apalutamide, a strong CYP3A4 inducer, with drugs that are CYP3A4 substrates can result in lower exposure to these medications. Avoid or substitute another drug for these medications when possible. Evaluate for loss of therapeutic effect if medication must be coadministered. Adjust dose according to prescribing information if needed.

              • bremelanotide

                bremelanotide will decrease the level or effect of ethosuximide by Other (see comment). Avoid or Use Alternate Drug. Bremelanotide may slow gastric emptying and potentially reduces the rate and extent of absorption of concomitantly administered oral medications. Avoid use when taking any oral drug that is dependent on threshold concentrations for efficacy. Interactions listed are representative examples and do not include all possible clinical examples.

              • brigatinib

                brigatinib will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Brigatinib induces CYP3A4 in vitro. Coadministration with CYP3A4 substrates, particularly those with a narrow therapeutic index, can result in decreased concentrations and loss of efficacy. If unable to avoid coadministration, monitor CYP3A4 substrate levels and adjust dose as needed.

              • calcium/magnesium/potassium/sodium oxybates

                ethosuximide, calcium/magnesium/potassium/sodium oxybates. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Profound sedation, respiratory depression, coma, and death may result if coadministered. Reserve concomitant prescribing of these drugs in patients for whom other treatment options are inadequate. Limit dosages and durations to the minimum required. Monitor closely for signs of respiratory depression and sedation.

              • conivaptan

                conivaptan will increase the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

              • enzalutamide

                enzalutamide will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

              • fexinidazole

                fexinidazole will increase the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Fexinidazole inhibits CYP3A4. Coadministration may increase risk for adverse effects of CYP3A4 substrates.

              • idelalisib

                idelalisib will increase the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Idelalisib is a strong CYP3A inhibitor; avoid coadministration with sensitive CYP3A substrates

              • ivosidenib

                ivosidenib will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP3A4 substrates with ivosidenib or replace with alternate therapies. If coadministration is unavoidable, monitor patients for loss of therapeutic effect of these drugs.

              • lumacaftor/ivacaftor

                lumacaftor/ivacaftor will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Lumacaftor is a strong inducer of CYP3A. Avoid coadministration with sensitive CYP3A substrates or CYP3A substrates with a narrow therapeutic index.

              • metoclopramide intranasal

                ethosuximide, metoclopramide intranasal. Either increases effects of the other by Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid use of metoclopramide intranasal or interacting drug, depending on importance of drug to patient.

              • mifepristone

                mifepristone will increase the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

              • mobocertinib

                mobocertinib will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If use is unavoidable, increase CYP3A4 substrate dosage in accordance with its prescribing information.

              • nefazodone

                nefazodone will increase the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

              • pacritinib

                pacritinib will increase the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

              • pexidartinib

                pexidartinib will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of pexidartinib (a CYP3A4 inducer) with sensitive CYP3A substrates may lead to serious therapeutic failures. If concomitant use is unavoidable, increase the CYP3A substrate dosage in accordance with approved product labeling.

              • primidone

                primidone will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

              • ropeginterferon alfa 2b

                ropeginterferon alfa 2b and ethosuximide both increase Other (see comment). Avoid or Use Alternate Drug. Narcotics, hypnotics or sedatives can produce additive neuropsychiatric side effects. Avoid use and monitor patients receiving the combination for effects of excessive CNS toxicity.

              • sodium oxybate

                ethosuximide, sodium oxybate. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Profound sedation, respiratory depression, coma, and death may result if coadministered. Reserve concomitant prescribing of these drugs in patients for whom other treatment options are inadequate. Limit dosages and durations to the minimum required. Monitor closely for signs of respiratory depression and sedation.

              • sotorasib

                sotorasib will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If use is unavoidable, refer to the prescribing information of the CYP3A4 substrate for dosage modifications

              • tucatinib

                tucatinib will increase the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid concomitant use of tucatinib with CYP3A substrates, where minimal concentration changes may lead to serious or life-threatening toxicities. If unavoidable, reduce CYP3A substrate dose according to product labeling.

              • voxelotor

                voxelotor will increase the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Voxelotor increases systemic exposure of sensitive CYP3A4 substrates. Avoid coadministration with sensitive CYP3A4 substrates with a narrow therapeutic index. Consider dose reduction of the sensitive CYP3A4 substrate(s) if unable to avoid.

              Monitor Closely (73)

              • amobarbital

                amobarbital will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              • atazanavir

                atazanavir increases levels of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity. .

              • belzutifan

                belzutifan will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If unable to avoid coadministration of belzutifan with sensitive CYP3A4 substrates, consider increasing the sensitive CYP3A4 substrate dose in accordance with its prescribing information.

              • berotralstat

                berotralstat will increase the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor or titrate substrate dose when berotralstat is coadministered with narrow therapeutic index drugs that are CYP3A substrates.

              • blinatumomab

                blinatumomab increases levels of ethosuximide by decreasing metabolism. Modify Therapy/Monitor Closely. Treatment initiation causes transient release of cytokines that may suppress CYP450 enzymes; highest drug-drug interaction risk is during the first 9 days of the first cycle and the first 2 days of the 2nd cycle in patients who are receiving concomitant CYP450 substrates, particularly those with a narrow therapeutic index.

              • bosentan

                bosentan will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              • brexanolone

                brexanolone, ethosuximide. Either increases toxicity of the other by sedation. Use Caution/Monitor.

              • carbamazepine

                carbamazepine will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              • cenobamate

                cenobamate will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Increase dose of CYP3A4 substrate, as needed, when coadministered with cenobamate.

                cenobamate, ethosuximide. Either increases effects of the other by sedation. Use Caution/Monitor.

              • clobazam

                ethosuximide, clobazam. Other (see comment). Use Caution/Monitor. Comment: Concomitant administration can increase the potential for CNS effects (e.g., increased sedation or respiratory depression).

              • cobicistat

                cobicistat will increase the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              • crizotinib

                crizotinib increases levels of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dose reduction may be needed for coadministered drugs that are predominantly metabolized by CYP3A.

              • crofelemer

                crofelemer increases levels of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Crofelemer has the potential to inhibit CYP3A4 at concentrations expected in the gut; unlikely to inhibit systemically because minimally absorbed.

              • dabrafenib

                dabrafenib will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.

              • daridorexant

                ethosuximide and daridorexant both increase sedation. Modify Therapy/Monitor Closely. Coadministration increases risk of CNS depression, which can lead to additive impairment of psychomotor performance and cause daytime impairment.

              • darunavir

                darunavir increases levels of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity. .

              • deutetrabenazine

                ethosuximide and deutetrabenazine both increase sedation. Use Caution/Monitor.

              • difelikefalin

                difelikefalin and ethosuximide both increase sedation. Use Caution/Monitor.

              • dulaglutide

                dulaglutide, ethosuximide. Other (see comment). Use Caution/Monitor. Comment: Dulaglutide slows gastric emptying and may impact absorption of concomitantly administered oral medications; be particularly cautious when coadministered with drugs that have a narrow therapeutic index.

              • duvelisib

                duvelisib will increase the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration with duvelisib increases AUC of a sensitive CYP3A4 substrate which may increase the risk of toxicities of these drugs. Consider reducing the dose of the sensitive CYP3A4 substrate and monitor for signs of toxicities of the coadministered sensitive CYP3A substrate.

              • efavirenz

                efavirenz will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              • elagolix

                elagolix will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Elagolix is a weak-to-moderate CYP3A4 inducer. Monitor CYP3A substrates if coadministered. Consider increasing CYP3A substrate dose if needed.

              • elvitegravir/cobicistat/emtricitabine/tenofovir DF

                elvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Cobicistat is a CYP3A4 inhibitor; contraindicated with CYP3A4 substrates for which elevated plasma concentrations are associated with serious and/or life-threatening events.

              • encorafenib

                encorafenib, ethosuximide. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Encorafenib both inhibits and induces CYP3A4 at clinically relevant plasma concentrations. Coadministration of encorafenib with sensitive CYP3A4 substrates may result in increased toxicity or decreased efficacy of these agents.

              • esketamine intranasal

                esketamine intranasal, ethosuximide. Either increases toxicity of the other by sedation. Use Caution/Monitor.

              • etravirine

                etravirine will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              • ferric maltol

                ferric maltol, ethosuximide. Either increases levels of the other by unspecified interaction mechanism. Modify Therapy/Monitor Closely. Coadministration of ferric maltol with certain oral medications may decrease the bioavailability of either ferric maltol and some oral drugs. For oral drugs where reductions in bioavailability may cause clinically significant effects on its safety or efficacy, separate administration of ferric maltol from these drugs. Duration of separation may depend on the absorption of the medication concomitantly administered (eg, time to peak concentration, whether the drug is an immediate or extended release product).

              • fosamprenavir

                fosamprenavir increases levels of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity. .

              • fosphenytoin

                fosphenytoin will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              • ganaxolone

                ethosuximide and ganaxolone both increase sedation. Use Caution/Monitor.

              • glycerol phenylbutyrate

                glycerol phenylbutyrate will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Glycerol phenylbutyrate is a weak inducer of CYP3A4. Monitor for decreased efficacy of CYP3A4 substrates that have a narrow therapeutic index.

              • iloperidone

                iloperidone increases levels of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Iloperidone is a time-dependent CYP3A inhibitor and may lead to increased plasma levels of drugs predominantly eliminated by CYP3A4.

              • indinavir

                indinavir will increase the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              • isavuconazonium sulfate

                isavuconazonium sulfate will increase the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              • istradefylline

                istradefylline will increase the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Istradefylline 40 mg/day increased peak levels and AUC of CYP3A4 substrates in clinical trials. This effect was not observed with istradefylline 20 mg/day. Consider dose reduction of sensitive CYP3A4 substrates.

              • itraconazole

                itraconazole will increase the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              • ixekizumab

                ixekizumab, ethosuximide. Other (see comment). Use Caution/Monitor. Comment: Formation of CYP450 enzymes can be altered by increased levels of certain cytokines during chronic inflammation; thus, ixekizumab could normalize the formation of CYP450 enzymes. Upon initiation or discontinuation of ixekizumab in patients who are receiving concomitant CYP450 substrates, particularly those with a narrow therapeutic index, consider monitoring for therapeutic effect.

              • ketoconazole

                ketoconazole will increase the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              • lemborexant

                ethosuximide, lemborexant. Either increases effects of the other by sedation. Modify Therapy/Monitor Closely. Dosage adjustment may be necessary if lemborexant is coadministered with other CNS depressants because of potentially additive effects.

              • letermovir

                letermovir increases levels of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              • levoketoconazole

                levoketoconazole will increase the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              • lopinavir

                lopinavir increases levels of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity.

              • lorlatinib

                lorlatinib will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              • lurasidone

                lurasidone, ethosuximide. Either increases toxicity of the other by Other (see comment). Use Caution/Monitor. Comment: Potential for increased CNS depressant effects when used concurrently; monitor for increased adverse effects and toxicity.

              • methylphenidate transdermal

                methylphenidate transdermal will increase the level or effect of ethosuximide by decreasing metabolism. Modify Therapy/Monitor Closely. Consider decreasing the dose of these drugs when given coadministered with methylphenidate. Monitor for drug toxiticities when initiating or discontinuing methylphenidate.

              • midazolam intranasal

                midazolam intranasal, ethosuximide. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Concomitant use of barbiturates, alcohol, or other CNS depressants may increase the risk of hypoventilation, airway obstruction, desaturation, or apnea and may contribute to profound and/or prolonged drug effect.

              • mitotane

                mitotane decreases levels of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Mitotane is a strong inducer of cytochrome P-4503A4; monitor when coadministered with CYP3A4 substrates for possible dosage adjustments.

              • nafcillin

                nafcillin will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              • nelfinavir

                nelfinavir increases levels of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity. .

              • oritavancin

                oritavancin will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Oritavancin is a weak CYP3A4 inducer; caution if coadministered with CYP3A4 substrates that have a narrow therapeutic index

              • orlistat

                orlistat decreases levels of ethosuximide by inhibition of GI absorption. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Risk of convulsions.

              • palbociclib

                palbociclib will increase the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. The dose of sensitive CYP3A substrates with a narrow therapeutic index may need to be reduced if coadministered with palbociclib

              • phenobarbital

                phenobarbital will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              • phenytoin

                phenytoin, ethosuximide. Other (see comment). Use Caution/Monitor. Comment: Ethosuximide may enhance CNS depressant effects and may increase serum concentrations of phenytoin. Phenytoin, a CYP3A4 inducer, may decrease plasma levels of ethosuximide (a CYP3A4 substrate.).

              • pitolisant

                pitolisant will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Pitolisant is a borderline/weak inducer of CYP3A4. Monitor sensitive CYP3A4 substrates for reduced effectiveness if coadministered.

              • posaconazole

                posaconazole will increase the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              • ribociclib

                ribociclib will increase the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Caution if ribociclib is coadministered with sensitive CYP3A4 substrates that have a narrow therapeutic index. Dose reduction for sensitive CYP3A4 substrates may be needed.

              • rifampin

                rifampin will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.

              • rifapentine

                rifapentine will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              • ritonavir

                ritonavir increases levels of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity.

              • rucaparib

                rucaparib will increase the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust dosage of CYP3A4 substrates, if clinically indicated.

              • saquinavir

                saquinavir increases levels of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity. .

              • secobarbital

                secobarbital will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. May also enhance CNS depressant effect of ethosuximide

              • secukinumab

                secukinumab, ethosuximide. Other (see comment). Use Caution/Monitor. Comment: Formation of CYP450 enzymes can be altered by increased levels of certain cytokines during chronic inflammation; thus, secukinumab could normalize the formation of CYP450 enzymes. Upon initiation or discontinuation of secukinumab in patients who are receiving concomitant CYP450 substrates, particularly those with a narrow therapeutic index, consider monitoring for therapeutic effect.

              • sevelamer

                sevelamer decreases levels of ethosuximide by increasing elimination. Use Caution/Monitor.

              • stiripentol

                stiripentol, ethosuximide. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Stiripentol is a CYP3A4 inhibitor and inducer. Monitor CYP3A4 substrates coadministered with stiripentol for increased or decreased effects. CYP3A4 substrates may require dosage adjustment.

                stiripentol, ethosuximide. Either increases effects of the other by sedation. Use Caution/Monitor. Concomitant use stiripentol with other CNS depressants, including alcohol, may increase the risk of sedation and somnolence.

              • tazemetostat

                tazemetostat will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              • tecovirimat

                tecovirimat will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Tecovirimat is a weak CYP3A4 inducer. Monitor sensitive CYP3A4 substrates for effectiveness if coadministered.

              • teduglutide

                teduglutide increases levels of ethosuximide by Other (see comment). Use Caution/Monitor. Comment: Teduglutide may increase absorption of concomitant PO medications; caution with with drugs requiring titration or those with a narrow therapeutic index; dose adjustment may be necessary.

              • telotristat ethyl

                telotristat ethyl will decrease the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Telotristat ethyl induces CYP3A4 and may reduce systemic exposure of sensitive CYP3A4 substrates. Monitor for suboptimal efficacy and consider increasing the dose of the CYP3A4 substrate.

              • tipranavir

                tipranavir increases levels of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity. .

              • ustekinumab

                ustekinumab, ethosuximide. Other (see comment). Use Caution/Monitor. Comment: Formation of CYP450 enzymes can be altered by increased levels of certain cytokines during chronic inflammation; thus, normalizing the formation of CYP450 enzymes. Upon initiation or discontinuation of ustekinumab in patients who are receiving concomitant CYP450 substrates, particularly those with a narrow therapeutic index, consider monitoring for therapeutic effect.

              • voriconazole

                voriconazole will increase the level or effect of ethosuximide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              Minor (31)

              • acetaminophen

                ethosuximide decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.

              • acetaminophen IV

                ethosuximide decreases levels of acetaminophen IV by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.

              • acetaminophen rectal

                ethosuximide decreases levels of acetaminophen rectal by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.

              • amobarbital

                ethosuximide decreases effects of amobarbital by pharmacodynamic antagonism. Minor/Significance Unknown.

              • atracurium

                ethosuximide decreases effects of atracurium by pharmacodynamic antagonism. Minor/Significance Unknown.

              • biotin

                ethosuximide decreases levels of biotin by unspecified interaction mechanism. Minor/Significance Unknown. Biotin supplementation may be necessary.

              • butabarbital

                ethosuximide decreases effects of butabarbital by pharmacodynamic antagonism. Minor/Significance Unknown.

              • butalbital

                ethosuximide decreases effects of butalbital by pharmacodynamic antagonism. Minor/Significance Unknown.

              • cisatracurium

                ethosuximide decreases effects of cisatracurium by pharmacodynamic antagonism. Minor/Significance Unknown.

              • cyanocobalamin

                ethosuximide decreases levels of cyanocobalamin by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.

              • dexmethylphenidate

                dexmethylphenidate increases effects of ethosuximide by decreasing metabolism. Minor/Significance Unknown.

              • dextroamphetamine

                dextroamphetamine decreases levels of ethosuximide by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.

              • ethotoin

                ethosuximide increases effects of ethotoin by pharmacodynamic synergism. Minor/Significance Unknown.

              • fosphenytoin

                ethosuximide increases effects of fosphenytoin by pharmacodynamic synergism. Minor/Significance Unknown.

              • levocarnitine

                ethosuximide decreases levels of levocarnitine by unspecified interaction mechanism. Minor/Significance Unknown.

              • lisdexamfetamine

                lisdexamfetamine decreases levels of ethosuximide by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.

              • methamphetamine

                methamphetamine decreases levels of ethosuximide by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.

              • methylenedioxymethamphetamine

                methylenedioxymethamphetamine decreases levels of ethosuximide by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.

              • onabotulinumtoxinA

                ethosuximide decreases effects of onabotulinumtoxinA by pharmacodynamic antagonism. Minor/Significance Unknown.

              • pancuronium

                ethosuximide decreases effects of pancuronium by pharmacodynamic antagonism. Minor/Significance Unknown.

              • pentobarbital

                ethosuximide decreases effects of pentobarbital by pharmacodynamic antagonism. Minor/Significance Unknown.

              • phenobarbital

                ethosuximide decreases effects of phenobarbital by pharmacodynamic antagonism. Minor/Significance Unknown.

              • phenytoin

                ethosuximide increases effects of phenytoin by pharmacodynamic synergism. Minor/Significance Unknown.

              • primidone

                ethosuximide decreases effects of primidone by pharmacodynamic antagonism. Minor/Significance Unknown.

              • rapacuronium

                ethosuximide decreases effects of rapacuronium by pharmacodynamic antagonism. Minor/Significance Unknown.

              • rocuronium

                ethosuximide decreases effects of rocuronium by pharmacodynamic antagonism. Minor/Significance Unknown.

              • sage

                sage decreases effects of ethosuximide by pharmacodynamic antagonism. Minor/Significance Unknown. Theoretical interaction; some species of sage may cause convulsions.

              • secobarbital

                ethosuximide decreases effects of secobarbital by pharmacodynamic antagonism. Minor/Significance Unknown.

              • serdexmethylphenidate/dexmethylphenidate

                serdexmethylphenidate/dexmethylphenidate increases effects of ethosuximide by decreasing metabolism. Minor/Significance Unknown.

              • succinylcholine

                ethosuximide decreases effects of succinylcholine by pharmacodynamic antagonism. Minor/Significance Unknown.

              • vecuronium

                ethosuximide decreases effects of vecuronium by pharmacodynamic antagonism. Minor/Significance Unknown.

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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

              Cases of systemic lupus erythematosus reported with use of drug; the physician should be alert to this possibility

              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

              The drug is capable of producing morphological and functional changes in animal liver; in humans, abnormal liver and renal function studies reported; ethosuximide should be administered with extreme caution to patients with known liver or renal disease; periodic urinalysis and liver function studies are advised for all patients receiving the drug

              May cause CNS depression

              Suicidal behavior and ideation

              • Anyone considering prescribing this drug or any other AED must balance risk of suicidal thoughts and behavior with risk of untreated illness
              • Antiepileptic drugs increase risk of suicidal thoughts or behavior in patients taking them for any indication; monitor for emergence or worsening of depression, suicidal thoughts or behavior, and/or any unusual changes in mood or behavior
              • Epilepsy and many other illnesses for which AEDs areprescribed are themselves associated with morbidity and mortality and an increased risk of suicidalthoughts and behavior
              • Should suicidal thoughts and behavior emerge during treatment, the prescriber needs to consider whether the emergence of these symptoms in any given patient may be related to the illness being treated
              • Behaviors of concern should be reported immediately to healthcare providers

              Thrombocytopenia

              • Drug-induced immune thrombocytopenia (DITP) reported; in reported cases, the onset of symptoms occurred 1 to 3 weeks after initiation of therapy; one patient had recurrence of symptoms within 1 day of a subsequent re-challenge with the drug
              • When DITP suspected, discontinue therapy; monitor serial platelet counts, and treat as appropriate; if possible, assess presence of drug- dependent antiplatelet antibodies; avoid future use of drug in patients with history of ethosuximide- induced DITP
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              Pregnancy & Lactation

              Pregnancy

              Drug crosses placenta; reports suggest an association between use of anticonvulsant drugs by women with epilepsy and elevated incidence of birth defects in children born to these women; data are more extensive with respect to phenytoin and phenobarbital, but these are also the most commonly prescribed anticonvulsants; less systematic or anecdotal reports suggest a possible similar association with the use of all known anticonvulsant drugs

              Cases of birth defects reported with this drug; reports suggesting an elevated incidence of birth defects in children of drug-treated epileptic women cannot be regarded as adequate to prove a definite cause and effect relationship

              There are intrinsic methodological problems in obtaining adequate data on drug teratogenicity in humans; the possibility also exists that other factors, eg, genetic factors or epileptic condition itself, maybe more important than drug therapy in leading to birth defects

              The great majority of mothers on anticonvulsant medication deliver normal infants; it is important to note that anticonvulsant drugs should not be discontinued in patients in whom the drug is administered to prevent major seizures because of the strong possibility of precipitating status epilepticus with attendant hypoxia and threat to life; in individual cases where severity and frequency of seizure disorder are such that removal of medication does not pose a serious threat to patient; discontinuation of drug may be considered prior to and during pregnancy

              Although it cannot be said with any confidence that even minor seizures do not pose some hazard to the developing embryo or fetus; the prescribing physician will wish to weigh these considerations in treating or counseling epileptic women of childbearing potential

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

              Lactation

              The drug is excreted in human breast milk; because effects of ethosuximide on nursing infant are unknown, use caution when administering to a nursing mother; the drug should be used in nursing mothers only if the benefits clearly outweigh the risks

              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

              BRAND FORM. UNIT PRICE PILL IMAGE
              Zarontin oral
              -
              250 mg capsule
              Zarontin oral
              -
              250 mg/5 mL solution
              ethosuximide oral
              -
              250 mg/5 mL solution
              ethosuximide oral
              -
              250 mg capsule
              ethosuximide oral
              -
              250 mg/5 mL solution
              ethosuximide oral
              -
              250 mg capsule
              ethosuximide oral
              -
              250 mg capsule
              ethosuximide oral
              -
              250 mg/5 mL solution
              ethosuximide oral
              -
              250 mg capsule

              Copyright © 2010 First DataBank, Inc.

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              Patient Handout

              Patient Education
              ethosuximide oral

              ETHOSUXIMIDE - ORAL

              (ETH-oh-SUX-i-mide)

              COMMON BRAND NAME(S): Zarontin

              USES: This medication is used alone or with other medications to prevent and control a certain type of seizure (absence or petit mal seizure). It works by controlling the abnormal electrical activity in the brain that occurs during a seizure.

              HOW TO USE: Read the Medication Guide provided by your pharmacist before you start taking this medication and each time you get a refill. If you have any questions, ask your doctor or pharmacist.Take this medication by mouth with or without food as directed by your doctor, usually once or twice daily.If you are using the liquid form of this medication, carefully measure the dose using a special measuring device/spoon. Do not use a household spoon because you may not get the correct dose.Dosage is based on your age, medical condition, blood levels of ethosuximide, and response to treatment. For children, the dosage may also be based on their weight.It is very important to follow your doctor's dosing instructions exactly. Your doctor will start you on a low dose and slowly increase your dose. It may take several weeks or months to reach the best dose for you and to get the full benefit from this medication. Use this medication regularly in order to get the most benefit from it. To help you remember, use it at the same time(s) each day.Do not stop taking this medication without consulting your doctor. Some conditions may become worse when the drug is suddenly stopped. Your dose may need to be gradually decreased.Tell your doctor if your condition does not improve or if it worsens.

              SIDE EFFECTS: Drowsiness, dizziness, tiredness, headache, stomach upset, loss of appetite, nausea, vomiting, weight loss, diarrhea, or loss of coordination may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.A small number of people who take anticonvulsants for any condition (such as seizure, bipolar disorder, pain) may experience depression, suicidal thoughts/attempts, or other mental/mood problems. Tell your doctor right away if you or your family/caregiver notice any unusual/sudden changes in your mood, thoughts, or behavior including signs of depression, suicidal thoughts/attempts, thoughts about harming yourself.Tell your doctor right away if you have any serious side effects, including: fainting, aching swollen joints, severe tiredness, easy bruising/bleeding, pink/bloody urine, rapid breathing.A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: fever, swollen lymph nodes, rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

              PRECAUTIONS: Before taking ethosuximide, tell your doctor or pharmacist if you are allergic to it; or to methsuximide; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.Before using this medication, tell your doctor or pharmacist your medical history, especially of: liver disease, kidney disease, mental/mood disorder (such as depression, psychosis).This drug may make you dizzy or drowsy. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Avoid alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).Liquid products may contain sugar and/or alcohol. Caution is advised if you have diabetes, alcohol dependence, liver disease, or any other condition that requires you to limit/avoid these substances in your diet. Ask your doctor or pharmacist about using this product safely.Older adults may be more sensitive to the side effects of this drug, especially dizziness, loss of coordination, or fainting. These side effects can increase the risk of falling.During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.This medication passes into breast milk, but is unlikely to harm a nursing infant. Consult your doctor before breast-feeding.

              DRUG INTERACTIONS: Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.A product that may interact with this drug is: orlistat.Tell your doctor or pharmacist if you are taking other products that cause drowsiness, including alcohol, marijuana (cannabis), antihistamines (such as cetirizine, diphenhydramine), drugs for sleep or anxiety (such as alprazolam, diazepam, zolpidem), muscle relaxants, and opioid pain relievers (such as codeine).Check the labels on all your medicines (such as allergy or cough-and-cold products) because they may contain ingredients that cause drowsiness. Ask your pharmacist about using those products safely.

              OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: slow/shallow breathing, severe drowsiness, loss of consciousness.

              NOTES: Do not share this medication with others.Laboratory and/or medical tests (such as ethosuximide blood levels, complete blood count, kidney/liver function) should be performed periodically to monitor your progress or check for side effects. Consult your doctor for more details.

              MISSED DOSE: It is important to take each dose at the scheduled time. If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

              STORAGE: Store at room temperature away from light and moisture. Do not freeze the liquid form of this medication. Do not store in the bathroom. Keep all medications away from children and pets.Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.

              MEDICAL ALERT: Your condition can cause complications in a medical emergency. For information about enrolling in MedicAlert, call 1-888-633-4298 (US) or 1-800-668-1507 (Canada).

              Information last revised December 2021. Copyright(c) 2022 First Databank, Inc.

              IMPORTANT: HOW TO USE THIS INFORMATION: This is a summary and does NOT have all possible information about this product. This information does not assure that this product is safe, effective, or appropriate for you. This information is not individual medical advice and does not substitute for the advice of your health care professional. Always ask your health care professional for complete information about this product and your specific health needs.

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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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              Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.