pharmacopeia
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/api/v1/drug/amifampridine

Mechanism of action

Sourced from openFDA

The mechanism by which amifampridine exerts its therapeutic effect in LEMS patients has not been fully elucidated. Amifampridine is a broad-spectrum potassium channel blocker.

Potassium Channel

Indications

Sourced from openFDA
  • FIRDAPSE ® is indicated for the treatment of Lambert-Eaton myasthenic syndrome (LEMS) in adults and pediatric patients 6 years of age and older. FIRDAPSE is a potassium channel blocker indicated for the treatment of Lambert-Eaton myasthenic syndrome (LEMS) in adults and pediatric patients 6 years of age and older.

Contraindications

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  • FIRDAPSE is contraindicated in patients with: A history of seizures [see Warnings and Precautions ( 5.1 )] Hypersensitivity to amifampridine phosphate or another aminopyridine [see Warnings and Precautions ( 5.2 )] FIRDAPSE is contraindicated in patients with: A history of seizures ( 4 ) Hypersensitivity to amifampridine or another aminopyridine ( 4 )contraindicated

Dosage & administration

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Administer orally in divided doses (3 to 5 times daily). ( 2.1 ) The recommended starting dosage for adults (any weight) and pediatric patients weighing 45 kg or more is 15 mg to 30 mg daily, in divided doses. ( 2.1 ) Dosage can be increased by 5 mg daily every 3 to 4 days. ( 2.1 ) The maximum single dose is 20 mg. ( 2.1 ) Dosage is not to exceed a maximum of 100 mg daily. ( 2.1 ) The recommended starting dosage for pediatric patients weighing less than 45 kg is 5 mg to 15 mg daily, in divided doses. ( 2.1 ) Dosage can be increased by 2.5 mg daily every 3 to 4 days. ( 2.1 ) The maximum single dose is 10 mg. ( 2.1 ) Dosage is not to exceed a maximum of 50 mg daily. ( 2.1 ) The recommended starting dosage for adult and pediatric patients with renal impairment, hepatic impairment, and in known N-acetyltransferase 2 (NAT2) poor metabolizers is the lowest recommended initial daily dosage ( 2.1 , 2.2 , 2.3 , 2.4 ) For patients with a dosage adjustment of less than 5 mg increments, or who have difficulty swallowing, or require feeding tube, a l mg/mL suspension can be prepared. ( 2.5 ) 2.1 Dosage Information The recommended oral dosage of FIRDAPSE for adults and pediatric patients 6 years of age and older is included in Table 1 . For pediatric patients, the recommended dosing regimen is dependent on body weight. Dosage should be increased every 3 to 4 days based on clinical response and tolerability. Titration increments should not exceed those shown in Table 1 .

Warnings & precautions

Sourced from openFDA

Seizures: FIRDAPSE can cause seizures. Consider discontinuation or dose-reduction of FIRDAPSE in patients who have a seizure while on treatment. ( 5.1 ) Hypersensitivity reactions: If a hypersensitivity reaction such as anaphylaxis occurs, FIRDAPSE should be discontinued and appropriate therapy initiated. ( 5.2 ) 5.1 Seizures FIRDAPSE can cause seizures. Seizures have been observed in patients without a history of seizures taking FIRDAPSE at the recommended doses, at various times after initiation of treatment, at an incidence of approximately 2%. Many of the patients were taking medications or had comorbid medical conditions that may have lowered the seizure threshold [see Drug Interactions ( 7.1 )]. Seizures may be dose-dependent. Consider discontinuation or dose-reduction of FIRDAPSE in patients who have a seizure while on treatment. FIRDAPSE is contraindicated in patients with a history of seizures. 5.2 Hypersensitivity In clinical trials, hypersensitivity reactions and anaphylaxis associated with FIRDAPSE administration have not been reported. Anaphylaxis has been reported in patients taking another aminopyridine; therefore, it may occur with FIRDAPSE. If anaphylaxis occurs, administration of FIRDAPSE should be discontinued and appropriate therapy initiated.

Adverse reactions

Sourced from openFDA

The following serious adverse reactions are described elsewhere in the labeling: Seizures [see Warnings and Precautions ( 5.1 )] Hypersensitivity [see Warnings and Precautions ( 5.2 )] The most common (> 10%) adverse reactions are: paresthesia, upper respiratory tract infection, abdominal pain, nausea, diarrhea, headache, elevated liver enzymes, back pain, hypertension, and muscle spasms. ( 6 ) To report SUSPECTED ADVERSE REACTIONS, contact Catalyst Pharmaceuticals at 1-844-347-3277 (1-844-FIRDAPSE) or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Trials Experience Adults Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. In controlled and uncontrolled clinical trials (Study 1 and 2) in patients with LEMS [see Clinical Studies ( 14 )] , 63 patients were treated with FIRDAPSE, including 40 patients treated for more than 6 months, and 39 patients treated for more than 12 months. In an expanded access program, 139 patients with LEMS were treated with FIRDAPSE, including 102 patients treated for more than 6 months, 77 patients treated for more than 12 months, and 53 patients treated for more than 18 months. In the expanded access program, patients were treated with FIRDAPSE with up to 100 mg daily in divided doses. Study 1 was a double-blind, placebo-controlled, randomized discontinuation study in adults with LEMS.

Use in specific populations

Sourced from openFDA

Pregnancy: Based on animal data, may cause fetal harm. ( 8.1 ) 8.1 Pregnancy Pregnancy Exposure Registry There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to FIRDAPSE during pregnancy. Physicians are encouraged to enroll pregnant patients, or pregnant women may register themselves in the registry by calling 855- 212-5856 (toll-free), using the Fax number 877-867-1874 (toll-free), by contacting the Pregnancy Coordinating Center at firdapsepregnancyregistry@ubc.com, or by visiting the study website www.firdapsepregnancystudy.com. Risk Summary There are no data on the developmental risk associated with the use of FIRDAPSE in pregnant women. In animal studies, administration of amifampridine phosphate to rats during pregnancy and lactation resulted in developmental toxicity (increase in stillbirths and pup deaths, reduced pup weight, and delayed sexual development) at doses associated with maternal plasma drug levels lower than therapeutic drug levels (see Animal Data ). In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively. The background risk of major birth defects and miscarriage for the indicated population is unknown.

Pharmacokinetics

Sourced from openFDA
Metabolism
The pharmacokinetics of amifampridine are similar between healthy individuals and LEMS patients. Following single and multiple doses, AUC, C max and C min were highly variable between individuals.

Overdosage

Sourced from openFDA

Overdose with FIRDAPSE was not reported during clinical studies. In a case report, a 65-year-old patient with LEMS inadvertently received a total daily amifampridine dose of 360 mg/day (approximately 4 times the maximum recommended total daily dose) and was hospitalized for general weakness, paresthesia, nausea, vomiting, and palpitations. The patient developed convulsions and paroxysmal supraventricular tachycardia, and four days after admission, experienced cardiac arrest. The patient was resuscitated and ultimately recovered following withdrawal of amifampridine. Patients with suspected overdose with FIRDAPSE should be monitored for signs or symptoms of exaggerated FIRDAPSE adverse reactions or effects, and appropriate symptomatic treatment instituted immediately.

Approval history

Sourced from openFDA
  • Nov 28, 2018NDANDA208078Catalyst Pharms

FAERS reports

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Reference statistics only. FAERS reports are voluntarily submitted and are not incidence rates, safety signals, or causal evidence. Counts reflect reporting volume — how often a reaction was reported, not how often it occurs. For decision-grade use, consult openFDA and the FAERS Public Dashboard directly.
2,776 total reports matchedLatest report Share = reports listing the reaction ÷ total matched reports. Rows can sum to >100% because a single report often lists multiple reactions.
  1. 1Asthenia33912%
  2. 2Drug Ineffective32512%
  3. 3Paraesthesia30811%
  4. 4Paraesthesia Oral2499.0%
  5. 5Fall2268.1%
  6. 6Fatigue1916.9%
  7. 7Nausea1866.7%
  8. 8Muscular Weakness1836.6%
  9. 9Condition Aggravated1806.5%
  10. 10Headache1726.2%
  11. 11Off Label Use1575.7%
  12. 12Diarrhoea1555.6%
  13. 13Dizziness1515.4%
  14. 14Dyspnoea1475.3%
  15. 15Product Dose Omission Issue1364.9%

Literature

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Recent PubMed references pinned to Amifampridine as a MeSH major topic. Citations link to pubmed.ncbi.nlm.nih.gov.

Clinical trials

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The 10 most recently updated of 23 ClinicalTrials.gov registrations naming Amifampridine as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

Pharmacogenomics

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CPIC-curated drug–gene pairs for Amifampridine. Levels describe the strength of curated evidence and guideline status — never a recommendation to test or to adjust therapy.

  • NAT2CPIC B/C (provisional)FDA label: Actionable PGx

Frequently asked questions

How does Amifampridine work?
The mechanism by which amifampridine exerts its therapeutic effect in LEMS patients has not been fully elucidated. Amifampridine is a broad-spectrum potassium channel blocker.
What is Amifampridine used for?
According to FDA labeling, Amifampridine carries indications including: FIRDAPSE ® is indicated for the treatment of Lambert-Eaton myasthenic syndrome (LEMS) in adults and pediatric patients 6 years of age and older. FIRDAPSE is a potassium channel blocker indicated for the treatment of Lambert-Eaton myasthenic syndrome (LEMS) in adults and pediatric patients 6 years of age and older.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.
What class of drug is Amifampridine?
Amifampridine is classified as Other nervous system drugs, Potassium Channel Blocker, Potassium Channel Antagonists, Increased Central Nervous System Acetylcholine Activity.
What are the brand names for Amifampridine?
Amifampridine is marketed under brand names including Firdapse.
What are the contraindications for Amifampridine?
Amifampridine labeling lists contraindications including: FIRDAPSE is contraindicated in patients with: A history of seizures [see Warnings and Precautions ( 5.1 )] Hypersensitivity to amifampridine phosphate or another aminopyridine [see Warnings and Precautions ( 5.2 )] FIRDAPSE is contraindicated in patients with: A history of seizures ( 4 ) Hypersensitivity to amifampridine or another aminopyridine ( 4 ). Always consult the full prescribing information and a clinician.
Note. Data for amifampridine is illustrative MVP content compiled from public sources. pharmacopeia is for educational and informational use only and is not a substitute for professional medical advice.

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