felbamate (Rx)

Brand and Other Names:Felbatol
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Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

tablets

  • 400 mg
  • 600 mg

oral suspension

  • 600 mg/5 mL

Seizures

Monotherapy

  • 1200 mg/day PO divided q6-8hr initially; titrate previously untreated patients with caution, increasing the dose in 600 mg increments q2weeks to 2400 mg/day based on clinial response and thereafter to 3600 mg/day if necessary

Conversion to monotherapy

  • Initial: 1200 mg/day PO divided q6-8hr; reduce dose of concomitant anticonvulsant(s) by 33% at initiation of felbamate therapy
  • Week 2: Increase felbamate dose to 2400 mg/day while reducing the dosage of other anticonvulsant(s) up to an additional 33% of original dosage
  • Week 3: Increase felbamate dose up to 3600 mg/day and continue to reduce dosage of other anticonvulsant(s) as clinically indicated

Adjunctive therapy

  • Initial: 1200 mg/day PO divided q6-8hr; increase by 1200 mg/day once per week up to 3600 mg/day PO divided q6-8hr
  • Decrease concomitant dose of carbamazepine, phenytoin, phenobarbital, or valproic acid by 20 % when intiating felbamate dosing; as felbamate dose is increased, further dosage reductions of concomitant anticonvulsant therapies may be necessary

Renal Impairment

Decreased intial and maintenance doses by 50%

Hepatic Impairment

Contraindicated

Dosage Forms & Strengths

tablets

  • 400 mg
  • 600 mg

oral suspension

  • 600 mg/5mL

Seizures

<14 years: Safety and efficacy not established

>14 years:

Monotherapy

  • 1200 mg/day PO divided q6-8hr initially; titrate previously untreated patients with caution, increasing the dose in 600 mg increments q2weeks to 2400 mg/day based on clinial response and thereafter to 3600 mg/day if necessary

Conversion to monotherapy

  • Initial: 1200 mg/day PO divided q6-8hr; reduce dose of concomitant anticonvulsant(s) by 33% at initiation of felbamate therapy
  • Week 2: Increase felbamate dose to 2400 mg/day while reducing the dosage of other anticonvulsant(s) up to an additional 33% of original dosage
  • Week 3: Increase felbamate dose up to 3600 mg/day and continue to reduce dosage of other anticonvulsant(s) as clinically indicated

Adjunctive therapy

  • Initial: 1200 mg/day PO divided q6-8hr; increase by 1200 mg/day once per week up to 3600 mg/day PO divided q6-8hr
  • Decrease concomitant dose of carbamazepine, phenytoin, phenobarbital, or valproic acid by 20 % when intiating felbamate dosing; as felbamate dose is increased, further dosage reductions of concomitant anticonvulsant therapies may be necessary

Lennox-Gastaut Adjunctive Therapy

<2 years

  • Safety and efficacy not established

2-14 years

  • Initial: 15 mg/kg/day PO divided q6-8hr
  • May increase to by 15 mg/kg/day qWeek to 45 mg/kg/day
  • Decrease concomitant dose of carbamazepine, phenytoin, phenobarbital, or valproic acid by 20 % when intiating felbamate dosing; as felbamate dose is increased, further dosage reductions of concomitant anticonvulsant therapies may be necessary
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Interactions

Interaction Checker

and felbamate

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            Contraindicated (1)

            • conivaptan

              conivaptan will increase the level or effect of felbamate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

            Serious - Use Alternative (25)

            • abametapir

              abametapir will increase the level or effect of felbamate 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 felbamate 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.

            • atazanavir

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

            • clarithromycin

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

            • clopidogrel

              felbamate decreases effects of clopidogrel by affecting hepatic enzyme CYP2C19 metabolism. Avoid or Use Alternate Drug. Clopidogrel efficacy may be reduced by drugs that inhibit CYP2C19. Inhibition of platelet aggregation by clopidogrel is entirely due to an active metabolite. Clopidogrel is metabolized to this active metabolite in part by CYP2C19. .

            • cobicistat

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

            • darunavir

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

            • enzalutamide

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

            • idelalisib

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

            • indinavir

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

            • itraconazole

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

            • ivosidenib

              ivosidenib will decrease the level or effect of felbamate 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.

            • lopinavir

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

            • mefloquine

              mefloquine increases toxicity of felbamate by QTc interval. Avoid or Use Alternate Drug. Mefloquine may enhance the QTc prolonging effect of high risk QTc prolonging agents.

            • metoclopramide intranasal

              felbamate, 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 felbamate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

            • nefazodone

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

            • nelfinavir

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

            • posaconazole

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

            • rifampin

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

            • ritonavir

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

            • saquinavir

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

            • tucatinib

              tucatinib will increase the level or effect of felbamate 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.

            • ulipristal

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

            • voxelotor

              voxelotor will increase the level or effect of felbamate 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 (58)

            • amitriptyline

              felbamate will increase the level or effect of amitriptyline by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor.

            • axitinib

              felbamate decreases levels of axitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • bosentan

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

            • brexanolone

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

            • carbamazepine

              carbamazepine decreases levels of felbamate by increasing metabolism. Use Caution/Monitor. Toxicity increased with combination.

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

            • carvedilol

              felbamate will increase the level or effect of carvedilol by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

            • cenobamate

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

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

            • crofelemer

              crofelemer increases levels of felbamate 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 felbamate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.

            • deutetrabenazine

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

            • dichlorphenamide

              dichlorphenamide and felbamate both decrease serum potassium. Use Caution/Monitor.

            • dienogest/estradiol valerate

              felbamate will decrease the level or effect of dienogest/estradiol valerate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Advise women to use alternative method of contraception or back-up method when moderate or weak enzyme inducer is used with combination contraceptives. Back-up contraception should be continued for 28 days after discontinuing medication to ensure contraceptive reliability.

            • duvelisib

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

            • elagolix

              elagolix decreases levels of felbamate 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 felbamate 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, felbamate. 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.

            • escitalopram

              felbamate will increase the level or effect of escitalopram by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor.

            • esketamine intranasal

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

            • ethotoin

              felbamate will increase the level or effect of ethotoin by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

            • etravirine

              felbamate will increase the level or effect of etravirine by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor.

              felbamate will increase the level or effect of etravirine by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

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

            • fedratinib

              fedratinib will increase the level or effect of felbamate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP3A4 substrates as necessary.

            • fosphenytoin

              felbamate will increase the level or effect of fosphenytoin by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

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

            • ibuprofen IV

              felbamate will increase the level or effect of ibuprofen IV by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

            • iloperidone

              iloperidone increases levels of felbamate 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.

            • imipramine

              felbamate will increase the level or effect of imipramine by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor.

            • istradefylline

              istradefylline will increase the level or effect of felbamate by affecting hepatic enzyme CYP2E1 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.

              istradefylline will increase the level or effect of felbamate 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.

            • ketoconazole

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

            • lasmiditan

              lasmiditan, felbamate. Either increases effects of the other by sedation. Use Caution/Monitor. Coadministration of lasmiditan and other CNS depressant drugs, including alcohol have not been evaluated in clinical studies. Lasmiditan may cause sedation, as well as other cognitive and/or neuropsychiatric adverse reactions.

            • lemborexant

              felbamate, 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.

            • levonorgestrel intrauterine

              felbamate decreases levels of levonorgestrel intrauterine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • levonorgestrel oral

              felbamate decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • linagliptin

              felbamate will increase the level or effect of linagliptin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of alternative treatments is strongly recommended when linagliptin is to be administered with a CYP3A4 inducer

            • lorlatinib

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

            • losartan

              felbamate will increase the level or effect of losartan by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor. May inhibit the conversion of losartan to its active metabolite E-3174. Importance of interaction not established; monitor individual therapeutic response to determine losartan dosage.

            • lurasidone

              lurasidone, felbamate. 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.

            • midazolam intranasal

              midazolam intranasal, felbamate. 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 felbamate 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 felbamate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

            • nateglinide

              felbamate will increase the level or effect of nateglinide by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

            • nevirapine

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

            • orlistat

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

            • parecoxib

              felbamate will increase the level or effect of parecoxib by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

            • phenobarbital

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

            • phenytoin

              felbamate will increase the level or effect of phenytoin by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

              phenytoin will decrease the level or effect of felbamate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Felbamate may increase serum concentrations of phenytoin. Phenytoin, a CYP3A4 inducer, may decrease plasma levels of felbamate (a CYP3A4 substrate).

            • primidone

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

            • ribociclib

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

            • rifabutin

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

            • rifapentine

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

            • rucaparib

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

            • secobarbital

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

            • sevelamer

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

            • stiripentol

              stiripentol, felbamate. 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, felbamate. 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 felbamate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

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

            • tecovirimat

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

            • ubrogepant

              felbamate will decrease the level or effect of ubrogepant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Dose adjustment is recommended with concomitant use of ubrogepant and moderate and weak CYP3A4 inducers. (see Dosage Modifications)

            • voriconazole

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

            • warfarin

              felbamate will increase the level or effect of warfarin by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.

            Minor (37)

            • acetaminophen

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

            • acetaminophen IV

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

            • acetaminophen rectal

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

            • alosetron

              felbamate will increase the level or effect of alosetron by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

            • atracurium

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

            • biotin

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

            • bosentan

              felbamate will increase the level or effect of bosentan by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

            • celecoxib

              felbamate will increase the level or effect of celecoxib by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

            • cimetidine

              felbamate will increase the level or effect of cimetidine by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

            • cisatracurium

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

            • cyanocobalamin

              felbamate 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 felbamate by decreasing metabolism. Minor/Significance Unknown.

            • diazepam

              felbamate will increase the level or effect of diazepam by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

            • diclofenac

              felbamate will increase the level or effect of diclofenac by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

            • ethinylestradiol

              felbamate decreases levels of ethinylestradiol by unknown mechanism. Minor/Significance Unknown.

            • ethotoin

              ethotoin decreases levels of felbamate by increasing metabolism. Minor/Significance Unknown. Toxicity increased with combination.

            • flurbiprofen

              felbamate will increase the level or effect of flurbiprofen by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

            • fosphenytoin

              fosphenytoin decreases levels of felbamate by increasing metabolism. Minor/Significance Unknown. Toxicity increased with combination.

            • ibuprofen

              felbamate will increase the level or effect of ibuprofen by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

            • levocarnitine

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

            • losartan

              felbamate decreases effects of losartan by decreasing metabolism. Minor/Significance Unknown. May inhibit the conversion of losartan to its active metabolite E-3174. Importance of interaction not established; monitor individual therapeutic response to determine losartan dosage.

            • meloxicam

              felbamate will increase the level or effect of meloxicam by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

            • mestranol

              felbamate decreases levels of mestranol by unknown mechanism. Minor/Significance Unknown.

            • onabotulinumtoxinA

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

            • pancuronium

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

            • phenobarbital

              felbamate increases levels of phenobarbital by decreasing metabolism. Minor/Significance Unknown.

            • piroxicam

              felbamate will increase the level or effect of piroxicam by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

            • rapacuronium

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

            • rocuronium

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

            • sage

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

            • succinylcholine

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

            • sulfamethoxazole

              felbamate will increase the level or effect of sulfamethoxazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

            • tolbutamide

              felbamate will increase the level or effect of tolbutamide by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

            • valproic acid

              valproic acid increases levels of felbamate by decreasing metabolism. Minor/Significance Unknown.

            • vecuronium

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

            • voriconazole

              felbamate will increase the level or effect of voriconazole by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

              felbamate will increase the level or effect of voriconazole by affecting hepatic enzyme CYP2C9/10 metabolism. Minor/Significance Unknown.

            • warfarin

              felbamate will increase the level or effect of warfarin by affecting hepatic enzyme CYP2C19 metabolism. Minor/Significance Unknown.

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            Adverse Effects

            >10%

            Adjunctive therapy

            • Nausea (34.2%)
            • Vomiting (16.7%)
            • Constipation (11.4%)
            • Dyspepsia (12.3%)
            • Anorexia (19.3%)
            • Dyspepsia (12.3%)

            Lennox-Gastaut

            • Anorexia (55%)
            • Somnolence (48%)
            • URI (46-50%)
            • Vomiting (39%)
            • Nervousness (16-20%)
            • Insomnia (16.1%)
            • Purpura (11-15%)
            • Fever (22.6%)
            • Constipation (12.9%)

            1-10%

            Monotherapy

            • Acne (3.4%)
            • Anxiety (5.2%)
            • Constipation (6.9%)
            • Diarrhea (5.2%)
            • Diplopia (3.4%)
            • Dyspepsia (8.6%)
            • Face edema (3.4%)
            • Fatigue (6.9%)
            • Headache (6.9%)
            • Insomnia (8.6%)
            • Intramenstrual bleeding (3.4%)
            • Otitis media (3.4%)
            • Rash (3.4%)
            • Urinary tract infection (3.4%)
            • Vomiting (8.6%)

            Adjunctive therapy

            • Abdominal pain (5.3%)
            • Abnormal gait (5.3%)
            • Anxiety (5.3%)
            • Ataxia (3.5%)
            • Depression (5.3%)
            • Increased ALT (3.5%)
            • Diarrhea (5.3%)
            • Dry mouth (2.6%)
            • Diplopia (6-10%)
            • Paresthesia (3.5%)
            • Pharyngitis (2.6%)
            • Stupor (2.6%)
            • Sinusitis (2-5%)
            • Tremor (6.1%)
            • Upper respiratory infection (5.3%)

            Lennox-Gastaut

            • Abnormal gait (9.7%)
            • Abnormal thoughts (6.5%)
            • Ataxia (6.5%)
            • Dyspepsia (6.5%)
            • Emotional lability (6.5%)
            • Fatigue (9.7%)
            • Headache (6.5%)
            • Hiccup (9.7%)
            • Leukopenia (6.5%)
            • Miosis (6.5%)
            • Nausea (6.5%)
            • Coughing (6.5%)
            • Pain (6.5%)
            • Pharyngitis (9.7%)
            • Otitis media (6-10%)

            <1%

            Atrial arrhythmia

            Bradycardia

            Hypotension

            Thrombophlebitis

            Cerebral edema

            Coma

            Alopecia

            Jaundice

            Hepatic failure

            Rigors

            Rhabdomyolysis

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            Warnings

            Black Box Warnings

            Aplastic anemia associated with felbamate use. Risk 100-fold in felbamate-treated patients compared with untreated population.

            May be fatal. Use only in patients with severe epilepsy in whom risk of aplastic anemia is acceptable.

            Acute liver failure reported with use; initiate use in patients with normal liver function.

            Contraindications

            Hypersensitivity to carbamates; history of blood dyscrasia, hepatic impairment

            Cautions

            Increased risk of suicidal behavior reported with anticonvulsant use; monitor patients for changes in behavior that might indicate suicidal behavior

            Associated with increased incidence of aplastic anemia and acute hepatic failure , use only when alternative therapy is unsuitable and benefits outweigh risks

            Use caution in renal impairment

            Not for use as first line therapy in epilepsy; for use when benefits outweigh risks

            Do not discontinue therapy abruptly

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            Pregnancy & Lactation

            Pregnancy Category: C

            Lactation: Excreted in milk; not recommended

            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

            Mechanism of action is unknown. Has weak inhibitory effects on GABA-receptor binding and benzodiazepine receptor binding.

            Pharmacokinetics

            Half-Life: 20-23 hr

            Peak Plasma: 17-49 mcg/mL (dose-dependent)

            Peak serum time: 3-5 hr

            Bioavailability: High

            Protein bound: 22-25%

            Vd: 756 mL/kg

            Metabolism: Liver

            Metabolites: Inactive

            Total body clearance: 26 mL/hr/kg (single dose); 30 mL/hr/kg (mult. doses)

            Excretion: Urine (80-90%)

            Enzyme induced: CYP3A4

            Enzyme inhibited: hepatic CYP2C19

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            Images

            BRAND FORM. UNIT PRICE PILL IMAGE
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            Felbatol oral
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            Felbatol oral
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            600 mg/5 mL suspension
            Felbatol oral
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            Felbatol oral
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            400 mg tablet

            Copyright © 2010 First DataBank, Inc.

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            Patient Handout

            Patient Education
            felbamate oral

            FELBAMATE - ORAL

            (fel-BAM-ate)

            COMMON BRAND NAME(S): Felbatol

            WARNING: Severe (sometimes fatal) blood/bone marrow problems (such as low red/white blood cells and platelets) and liver problems have occurred with felbamate. Felbamate should be used only by people with severe seizures (epilepsy) that cannot be controlled with other medications. Do not use this drug if you have liver problems. Discuss the risks and benefits with your doctor before starting felbamate.Tell your doctor right away if you have signs of infection (such as sore throat that doesn't go away, fever, chills), signs of anemia (such as unusual tiredness), easy bruising/bleeding, or signs of liver problems (such as nausea/vomiting that doesn't stop, stomach/abdominal pain, yellowing eyes/skin, dark urine). Usually, people who have liver problems while taking this drug should not start taking it again.Your doctor will check certain blood tests (liver function, complete blood count) and may have you see a doctor who treats blood/bone marrow problems before you start felbamate and while you use this drug. Blood/bone marrow problems may also occur after you stop taking the drug. Blood tests may be needed for some time after you stop taking felbamate. Keep all medical and lab appointments.

            USES: Felbamate is used to treat severe seizures. This medication should be used only when you cannot take other medications or when other medications have not been able to control your seizures. Felbamate is known as an anticonvulsant or anti-epileptic drug.

            HOW TO USE: Read and sign the Informed Consent form provided by your doctor. Read the Medication Guide provided by your pharmacist before you start taking felbamate and each time you get a refill. If you have any questions, ask your doctor or pharmacist before starting felbamate.Take this medication by mouth with or without food as directed by your doctor, usually 3 to 4 times a day. Take with food or milk if stomach upset occurs.If you are using the liquid form of this medication, shake the bottle well before each dose. Carefully measure the dose using a special measuring device/spoon. Do not use a household spoon because you may not get the correct dose.The dosage is based on your medical condition and response to treatment. For children, the dosage is also based on weight. To reduce your risk of side effects, your doctor may direct you to start this medication at a low dose and gradually increase your dose.Take this medication regularly to get the most benefit from it. To help you remember, take it at the same times each day.Do not stop taking this medication without consulting your doctor. Seizures may become worse when this drug is suddenly stopped. Your dose may need to be gradually decreased.If you are already taking other anti-seizure medications, carefully follow your doctor's directions for adjusting the dose of these other medications when you start taking felbamate.Tell your doctor if your seizures get worse.

            SIDE EFFECTS: See also Warning section.Drowsiness, dizziness, nausea, vomiting, diarrhea, constipation, trouble sleeping, loss of coordination, headache, blurred/double vision, hiccups, or loss of appetite may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.Remember that your doctor has prescribed this medication because he or she 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.Tell your doctor right away if you have any serious side effects, including: fainting.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 such as signs of depression, suicidal thoughts/attempts, thoughts about harming yourself.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: 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 felbamate, tell your doctor or pharmacist if you are allergic to it; or to meprobamate; 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: blood/bone marrow disorders (such as anemia, bleeding problems, low white blood cell count), liver disease, kidney disease, mental/mood disorders (such as depression, suicidal thoughts).This drug may make you dizzy or drowsy or blur your vision. It may also cause double vision. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness or clear vision until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).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. Because of the possible risk to the infant, breast-feeding while using this drug is not recommended. 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.Some products that may interact with this drug include: clopidogrel, orlistat.This medication may decrease the effectiveness of hormonal birth control such as pills, patch, or ring. This could cause pregnancy. Discuss with your doctor or pharmacist if you should use reliable backup birth control methods while using this medication. Also tell your doctor if you have any new spotting or breakthrough bleeding, because these may be signs that your birth control is not working well.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 (such as carisoprodol, cyclobenzaprine), and opioid pain relievers (such as codeine, hydrocodone).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.

            NOTES: Do not share this medication with others.Lab and/or medical tests (such as complete blood count, kidney/liver tests) should be done before, during, and after treatment with this medication. See also Warning section.

            MISSED DOSE: 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 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 March 2020. Copyright(c) 2021 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.