amifampridine (Rx)

Brand and Other Names:Firdapse, Ruzurgi
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Dosing & Uses

AdultPediatricGeriatric

Dosage Forms & Strengths

tablet

  • 10mg

Lambert-Eaton Myasthenic Syndrome

Indicated for Lambert-Eaton myasthenic syndrome (LEMS)

15-30 mg/day PO in divided doses (3-4 times daily) initially; may increase by 5 mg/day q3-4 days; not to exceed 80 mg/day

Maximum single dose: 20 mg

Dosage Modifications

Renal impairment

  • CrCl 15-90 mL/min: Recommended starting dose is 15 mg/day PO in 3 divided doses; monitor closely; consider dosage modification or discontinuation if needed based on effect and tolerability
  • End-stage renal disease (CrCl <15 mL/min): No recommendation can be made

Hepatic impairment

  • Not studied
  • Extensively metabolized by N-acetyltransferase 2 (NAT2), and hepatic impairment may cause an increase in exposure
  • Recommended starting dose: 15 mg/day PO in 3 divided doses; monitor closely
  • Consider dosage modification or discontinuation if needed based on effect and tolerability

NAT2 poor metabolizers

  • Recommended starting dose: 15 mg/day PO in 3 divided doses; monitor closely
  • Consider dosage modification needed based on clinical effect and tolerability

Myasthenia Gravis (Orphan)

Orphan designation for treatment of myasthenia gravis

Sponsor

  • Catalyst Pharmaceuticals, Inc; 355 Alhambra Circle Suite 1250; Coral Gables, Florida 33134

Dosage Forms & Strengths

tablet

  • 10mg (Ruzurgi)

Lambert-Eaton Myasthenic Syndrome

Ruzurgi only

Indicated for Lambert-Eaton myasthenic syndrome (LEMS) in patients aged 6 to <17 years

<6 years: Safety and efficacy not established

6 to <17 years and weighing <45 kg

  • 7.5-15 mg/day, in divided doses (2-3 times/day) initially
  • May increase based on clinical response and tolerability by 2.5- to 5-mg increments, divided in up to 5 doses/day
  • Maximum single dose is 15 mg; not to exceed 50 mg/day

6 to <17 years and weighing ≥45 kg

  • 15-30 mg PO daily in divided doses (2-3 times/day) initially
  • May increase based on clinical response and tolerability by 5- to 10-mg increments, divided in up to 5 dose/day
  • Maximum single dose is 30 mg; not to exceed 100 mg/day

Congenital Myasthenic Syndromes (Orphan)

Orphan designation for treatment of congenital myasthenic syndromes

Sponsor

  • Catalyst Pharmaceuticals, Inc; Suite 1500; Coral Gables, Florida 33134

Dosage Modifications

Known N-acetyltransferase 2 (NAT2) poor metabolizers

  • Starting dose <45 kg: 7.5 mg/day PO in divided doses
  • Starting dose ≥45 kg: 15 mg/day PO in divided doses

Renal impairment

  • <45 kg
    • Starting dose; CrCl 15-90 mL/min: 7.5 mg/day PO in divided doses
  • ≥45 kg
    • Starting dose; CrCl 15-90 mL/min: 15 mg/day PO in divided doses
  • Patients with CrCl <15 mL/min or end-stage renal disease: No dosage adjustments can be recommended

Hepatic impairment

  • <45 kg
    • Starting dose; CrCl 15-90 mL/min: 15 mg/day PO in divided doses
  • ≥45 kg
    • Starting dose for any degree of hepatic impairment: 15 mg/day PO in divided doses

In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy

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Interactions

Interaction Checker

and amifampridine

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                Monitor Closely (87)

                • acetylcholine

                  amifampridine and acetylcholine both increase cholinergic effects/transmission. Use Caution/Monitor.

                • amantadine

                  amantadine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • amitriptyline

                  amitriptyline increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • amoxapine

                  amoxapine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • baclofen

                  baclofen increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • bethanechol

                  amifampridine and bethanechol both increase cholinergic effects/transmission. Use Caution/Monitor.

                • bromocriptine

                  bromocriptine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • brompheniramine

                  brompheniramine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • bupropion

                  bupropion increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • carbachol

                  amifampridine and carbachol both increase cholinergic effects/transmission. Use Caution/Monitor.

                • cefepime

                  cefepime increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • cetirizine

                  cetirizine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • chlorpheniramine

                  chlorpheniramine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • chlorpromazine

                  chlorpromazine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • ciprofloxacin

                  ciprofloxacin increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • citalopram

                  citalopram increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • clemastine

                  clemastine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • clomipramine

                  clomipramine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • clozapine

                  clozapine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • cocaine

                  cocaine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • cyproheptadine

                  cyproheptadine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • delafloxacin

                  delafloxacin increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • desipramine

                  desipramine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • desloratadine

                  desloratadine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • dexchlorpheniramine

                  dexchlorpheniramine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • diphenhydramine

                  diphenhydramine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • donepezil

                  amifampridine and donepezil both increase cholinergic effects/transmission. Use Caution/Monitor.

                • doxepin

                  doxepin increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • doxylamine

                  doxylamine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • droperidol

                  droperidol increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • echothiophate iodide

                  amifampridine and echothiophate iodide both increase cholinergic effects/transmission. Use Caution/Monitor.

                • erythromycin base

                  erythromycin base increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • erythromycin ethylsuccinate

                  erythromycin ethylsuccinate increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • erythromycin lactobionate

                  erythromycin lactobionate increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • erythromycin stearate

                  erythromycin stearate increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • escitalopram

                  escitalopram increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • fentanyl

                  fentanyl increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • fexofenadine

                  fexofenadine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • flumazenil

                  flumazenil increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • fluoxetine

                  fluoxetine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • fluphenazine

                  fluphenazine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • fluvoxamine

                  fluvoxamine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • galantamine

                  amifampridine and galantamine both increase cholinergic effects/transmission. Use Caution/Monitor.

                • gemifloxacin

                  gemifloxacin increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • haloperidol

                  haloperidol increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • hydroxyzine

                  hydroxyzine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • imipramine

                  imipramine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • isoniazid

                  isoniazid increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • ketamine

                  ketamine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • levocetirizine

                  levocetirizine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • levofloxacin

                  levofloxacin increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • linezolid

                  linezolid increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • loratadine

                  loratadine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • loxapine

                  loxapine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • meclizine

                  meclizine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • meperidine

                  meperidine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • meropenem

                  meropenem increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • metronidazole

                  metronidazole increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • molindone

                  molindone increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • moxifloxacin

                  moxifloxacin increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • neostigmine

                  amifampridine and neostigmine both increase cholinergic effects/transmission. Use Caution/Monitor.

                • nortriptyline

                  nortriptyline increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • ofloxacin

                  ofloxacin increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • paroxetine

                  paroxetine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • penicillin G aqueous

                  penicillin G aqueous increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • penicillin G benzathine

                  penicillin G benzathine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • penicillin G procaine

                  penicillin G procaine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • penicillin VK

                  penicillin VK increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • perphenazine

                  perphenazine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • physostigmine

                  amifampridine and physostigmine both increase cholinergic effects/transmission. Use Caution/Monitor.

                • pilocarpine

                  amifampridine and pilocarpine both increase cholinergic effects/transmission. Use Caution/Monitor.

                • pilocarpine ophthalmic

                  amifampridine and pilocarpine ophthalmic both increase cholinergic effects/transmission. Use Caution/Monitor.

                • pimozide

                  pimozide increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • prochlorperazine

                  prochlorperazine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • promethazine

                  promethazine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • protriptyline

                  protriptyline increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • pyridostigmine

                  amifampridine and pyridostigmine both increase cholinergic effects/transmission. Use Caution/Monitor.

                • rivastigmine

                  amifampridine and rivastigmine both increase cholinergic effects/transmission. Use Caution/Monitor.

                • sertraline

                  sertraline increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • theophylline

                  theophylline increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • thioridazine

                  thioridazine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • thiothixene

                  thiothixene increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • tramadol

                  tramadol increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • trifluoperazine

                  trifluoperazine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • trimipramine

                  trimipramine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • triprolidine

                  triprolidine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                • venlafaxine

                  venlafaxine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

                Minor (0)

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                  Adverse Effects

                  >10% (Firdapse)

                  Paresthesia (62%)

                  Upper respiratory tract infection (33%)

                  Abdominal pain (14%)

                  Nausea (14%)

                  Diarrhea (14%)

                  Headache (14%)

                  Elevated liver enzymes (14%)

                  Back pain (14%)

                  Hypertension (12%)

                  Muscle spasms (12%)

                  >10% (Ruzurgi)

                  Paresthesia/dysesthesia (69%)

                  Abdominal pain (25%)

                  Dyspepsia (17%)Dizziness (12%)

                  1-10% (Firdapse)

                  Dizziness (10%)

                  Asthenia (10%)

                  Muscular weakness (10%)

                  Pain in extremity (10%)

                  Cataract (10%)

                  Constipation (7%)

                  Bronchitis (7%)

                  Fall (7%)

                  Lymphadenopathy (7%)

                  Seizures (2%)

                  1-10% (Ruzurgi)

                  Nausea (10%)

                  Back pain (8%)

                  Hypoesthesia (6%)

                  Muscle spasms (6%)

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                  Warnings

                  Contraindications

                  History of seizures

                  Hypersensitivity to amifampridine phosphate or another aminopyridine

                  Cautions

                  If hypersensitivity reaction (eg, anaphylaxis) occurs, discontinue drug and initiate appropriate therapy

                  Seizures

                  • Can cause seizures; consider discontinuation or dose reduction in patients who have a seizure while on treatment
                  • Many instances of seizure were in patients taking medications or who had comorbid conditions that may have lowered seizure threshold
                  • Contraindicated in patients with history of seizures

                  Drug interactions overview

                  • Drugs that lower seizure threshold: Coadministration may increase risk of seizures
                  • Drugs with cholinergic effects: Coadministration may increase risk of adverse cholinergic effects
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                  Pregnancy

                  Pregnancy

                  No data are available in pregnant women

                  Based on animal studies, can cause fetal harm (eg, still births, reduced fetal weight, delayed sexual development) at doses associated with maternal plasma drug levels lower than therapeutic drug levels

                  Pregnancy exposure registry

                  • Monitors pregnancy outcomes in women exposed during pregnancy
                  • Encourage pregnant patients, or pregnant women may register in the registry by calling 855-212-5856, using the fax number 877-867-1874, by contacting the Pregnancy Coordinating Center at firdapsepregnancyregistry@ubc.com, or by visiting the study website www.firdapsepregnancystudy.com

                  Lactation

                  Unknown if distributed in human breast milk

                  In lactating rats, amifampridine was excreted in milk and reached levels similar to those in maternal plasma

                  Consider the developmental and health benefits of breastfeeding along with the mother’s clinical need for the drug, and any potential adverse effects on the breastfed infant from the drug or from the underlying maternal condition

                  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

                  Blocks voltage-dependent potassium channels, thereby prolonging presynaptic cell membrane depolarization, which enhances calcium transport into nerve endings

                  The increased intracellular calcium concentrations facilitate exocytosis of acetylcholine-containing vesicles, which, in turn, enhances neuromuscular transmission

                  Absorption

                  Peak plasma time: 20-60 min (Firdapse); 30 min (Ruzurgi)

                  Compare with fasting state, administration of Ruzurgi 20- and 30-mg dose levels with a standard high-fat meal resulted in a significant decrease in AUC and peak plasma concentration and increase in peak plasma time

                  Distribution

                  Vd: Moderate to high (Ruzurgi)

                  Protein bound: 25.3 (amifampridine); 43.3% (3-N-acetyl amifampridine)

                  Metabolism

                  Extensively metabolized by N-acetyltransferase gene 2 (NAT2) in the liver to 3-N-acetyl-amifampridine (inactive)

                  Elimination

                  Half-life: 1.8-2.5 hr (healthy volunteers; Firdapse); 3.6-4.2 hr (Ruzurgi); 4.1-4.8 hr (3-N-acetyl amifampridine metabolite)

                  Oral clearance: 149-214 L/hr (Ruzurgi)

                  Excretion (as amifampridine or inactive metabolite): 93-100% in urine (Firdapse); >65% in urine (Ruzurgi)

                  Pharmacogenetics

                  Genetic variants in NAT2 affect rate and extent of metabolism

                  Poor metabolizers (ie, carriers of 2 reduced-function alleles) have 3.5- to 4.5-fold higher Cmax and 5.6- to 9-fold higher AUC than normal or fast metabolizers (ie, fast acetylators)

                  In the general population, the NAT2 poor metabolizer phenotype prevalence is 40-60% in white and African American populations and 10-30% in Asian ethnic populations

                  See Dosage Modifications

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                  Administration

                  Oral Suspension Preparation (Ruzurgi)

                  Patients requiring a dosage in <5-mg increments, have difficulty swallowing, or require feeding tubes: 1 mg/mL suspension can be prepared

                  Place three 10-mg tablets in a 30-mL container; crushing tablets prior to making the suspension is not necessary

                  Add 30 mL of sterile water

                  Shake well for 30 seconds

                  Oral Administration

                  May administer with or without food

                  Missed dose: Do not take double or extra doses

                  Extemporaneously compounded suspension (Ruzurgi)

                  • After preparation of suspension, draw up dose with an oral syringe and administer the correct dose by mouth or by feeding tube
                  • Shake well before drawing up each dose

                  Storage

                  Tablets (Firdapse): Store at 68-77°F (20-25°C); excursions permitted from 15-30°C (59-86°F)

                  Tablets (Ruzurgi)

                  • Prior to dispensing: Refrigerate 2-8°C (36-46°F); keep container tightly closed with desiccant canister inside after opening; protect from moisture and light
                  • After dispensing: Store at 20-25°C (68-77°F) for up to 3 months; excursions permitted to 15-30°C (59-86°F)

                  Extemporaneously compounded suspension (Ruzurgi)

                  • Refrigerate for up to 24 hr; discard remaining suspension after 24 hr
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                  Images

                  BRAND FORM. UNIT PRICE PILL IMAGE
                  Firdapse oral
                  -
                  10 mg tablet

                  Copyright © 2010 First DataBank, Inc.

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                  Patient Handout

                  A Patient Handout is not currently available for this monograph.
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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.