Firdapse

openFDA label record#

This page contains supplementary openFDA label data. For the canonical label presentation, use the corresponding DailyMed Structured Product Label.

Verified complete openFDA source JSON (canonical bytes are SHA-256 checked before publication)

Brand name
Firdapse
Generic name
AMIFAMPRIDINE PHOSPHATE
Manufacturer
Catalyst Pharmaceuticals, Inc.
Product type
HUMAN PRESCRIPTION DRUG
SPL set ID
f015fe60-3128-4a43-8c31-19fc6b5def3f
SPL ID
4f94edd2-b6a8-264d-e063-6294a90a89df
Version
15
Effective date
2026-04-16
Source export date
2026-09-28
Source partition
11
Source file
https://download.open.fda.gov/drug/label/drug-label-0011-of-0014.json.zip
Source object key
raw/openfda/drug-label/2026-09-28/aa96b5a2be6b394393acd0090f6948bdf99e0e8e00666f81608929c8fa83db77/drug-label-0011-of-0014.json.zip
Source manifest SHA-256
cd2e66336a5cd2223fa3995098fdbdb84c6a7ee5c0a4addb236ccb22dd1e6887
Import run
20260929T050834Z
Imported at
2026-09-29 06:17:38
Harmonized routes table
Harmonized routes
ORAL

Warnings cross-check#

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Warnings sections page 1 of 1 · 1 matching rows.

warnings and cautions

5 WARNINGS AND PRECAUTIONS 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 cross-check#

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Adverse reactions sections page 1 of 1 · 2 matching rows.

adverse reactions

6 ADVERSE REACTIONS 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. Following an initial open- label run-in phase (up to 90 days), patients were randomized to either continue FIRDAPSE treatment or transition to placebo, for a 14-day double-blind phase. Following final assessments, patients were allowed to resume FIRDAPSE treatment for up to 2 years (open-label long-term safety phase of the study). During the open-label run-in phase of Study 1, 53 patients received FIRDAPSE for an average of 81 days at a mean daily dosage of 50.5 mg/day. The mean patient age was 52.1 years and 66% were female. There were 42 patients who had no prior exposure to FIRDAPSE at the initiation of this study. Table 2 shows adverse reactions with an incidence of 5% or greater occurring in the 42 LEMS patients newly initiated on treatment with FIRDAPSE during the run-in phase of the study. Table 2. Adverse Reactions in ≥5% of LEMS Patients Newly Treated with FIRDAPSE in Study 1 *Includes paresthesia, oral paresthesia, oral hypoesthesia **Includes elevated alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and gamma-glutamyl transferase (GGT) Adverse Reaction FIRDAPSE N=42 % 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 Dizziness 10 Asthenia 10 Muscular weakness 10 Pain in extremity 10 Cataract 10 Constipation 7 Bronchitis 7 Fall 7 Lymphadenopathy 7 Other Adverse Reactions In the overall population treated in Study 1 (n=53), including the double-blind phase and the 2-year open-label long-term safety phase, additional adverse reactions occurring in at least 5% of the patients included: dyspnea, urinary tract infection, gastroesophageal reflux, insomnia, peripheral edema, pyrexia, viral infection, blood creatine phosphokinase increase, depression, erythema, hypercholesterolemia, and influenza. These patients received a mean daily dosage of 66 mg of FIRDAPSE. Pediatrics Safety of FIRDAPSE was evaluated in pediatric patients in an expanded access program, where 21 pediatric patients received FIRDAPSE for at least 1 year. Adverse reactions reported in pediatric patients were similar to those seen in adult patients, with the exception of clinically significant weight loss in two pediatric patients at doses of 60 mg per day and higher.

adverse reactions table

<table ID="t2" width="100%"><caption>Table 2. Adverse Reactions in &#x2265;5% of LEMS Patients Newly Treated with FIRDAPSE in Study 1</caption><col width="50.000%" align="left"/><col width="50.000%" align="left"/><tfoot><tr><td colspan="2" align="left" valign="top"><paragraph styleCode="footnote">*Includes paresthesia, oral paresthesia, oral hypoesthesia</paragraph></td></tr><tr><td colspan="2" align="left" valign="top"><paragraph styleCode="footnote">**Includes elevated alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and gamma-glutamyl transferase (GGT)</paragraph></td></tr></tfoot><tbody><tr><td align="center" styleCode="Toprule Botrule Lrule" valign="top"><content styleCode="bold">Adverse Reaction</content></td><td align="center" styleCode="Toprule Botrule Rrule" valign="top"><content styleCode="bold">FIRDAPSE N=42 </content> <content styleCode="bold">%</content></td></tr><tr><td align="left" styleCode="Lrule" valign="top">Paresthesia*</td><td align="center" styleCode="Rrule" valign="top">62</td></tr><tr><td align="left" styleCode="Lrule" valign="top">Upper respiratory tract infection</td><td align="center" styleCode="Rrule" valign="top">33</td></tr><tr><td align="left" styleCode="Lrule" valign="top">Abdominal pain</td><td align="center" styleCode="Rrule" valign="top">14</td></tr><tr><td align="left" styleCode="Lrule" valign="top">Nausea</td><td align="center" styleCode="Rrule" valign="top">14</td></tr><tr><td align="left" styleCode="Lrule" valign="top">Diarrhea</td><td align="center" styleCode="Rrule" valign="top">14</td></tr><tr><td align="left" styleCode="Lrule" valign="top">Headache</td><td align="center" styleCode="Rrule" valign="top">14</td></tr><tr><td align="left" styleCode="Lrule" valign="top">Elevated liver enzymes**</td><td align="center" styleCode="Rrule" valign="top">14</td></tr><tr><td align="left" styleCode="Lrule" valign="top">Back pain</td><td align="center" styleCode="Rrule" valign="top">14</td></tr><tr><td align="left" styleCode="Lrule" valign="top">Hypertension</td><td align="center" styleCode="Rrule" valign="top">12</td></tr><tr><td align="left" styleCode="Lrule" valign="top">Muscle spasms</td><td align="center" styleCode="Rrule" valign="top">12</td></tr><tr><td align="left" styleCode="Lrule" valign="top">Dizziness</td><td align="center" styleCode="Rrule" valign="top">10</td></tr><tr><td align="left" styleCode="Lrule" valign="top">Asthenia</td><td align="center" styleCode="Rrule" valign="top">10</td></tr><tr><td align="left" styleCode="Lrule" valign="top">Muscular weakness</td><td align="center" styleCode="Rrule" valign="top">10</td></tr><tr><td align="left" styleCode="Lrule" valign="top">Pain in extremity</td><td align="center" styleCode="Rrule" valign="top">10</td></tr><tr><td align="left" styleCode="Lrule" valign="top">Cataract</td><td align="center" styleCode="Rrule" valign="top">10</td></tr><tr><td align="left" styleCode="Lrule" valign="top">Constipation</td><td align="center" styleCode="Rrule" valign="top">7</td></tr><tr><td align="left" styleCode="Lrule" valign="top">Bronchitis</td><td align="center" styleCode="Rrule" valign="top">7</td></tr><tr><td align="left" styleCode="Lrule" valign="top">Fall</td><td align="center" styleCode="Rrule" valign="top">7</td></tr><tr><td align="left" styleCode="Botrule Lrule" valign="top">Lymphadenopathy</td><td align="center" styleCode="Botrule Rrule" valign="top">7</td></tr></tbody></table>

Reported adverse events (FAERS/openFDA)#

Adverse event summaries are temporarily unavailable. Other product information remains available.