U.S. Department of Health & Human Services Divider Arrow National Institutes of Health Divider Arrow NCATS

Details

Stereochemistry ACHIRAL
Molecular Formula C5H7N3.H3O4P
Molecular Weight 207.1244
Optical Activity NONE
Defined Stereocenters 0 / 0
E/Z Centers 0
Charge 0

SHOW SMILES / InChI
Structure of AMIFAMPRIDINE PHOSPHATE

SMILES

OP(O)(O)=O.NC1=CC=NC=C1N

InChI

InChIKey=KAICRBBQCRKMPO-UHFFFAOYSA-N
InChI=1S/C5H7N3.H3O4P/c6-4-1-2-8-3-5(4)7;1-5(2,3)4/h1-3H,7H2,(H2,6,8);(H3,1,2,3,4)

HIDE SMILES / InChI
Amifampridine (Firdapse), currently approved in the European Union, is the first and only approved drug for the symptomatic treatment of Lambert-Eaton Myasthenic Syndrome (LEMS) in adults, a rare autoimmune disease with the primary symptoms of muscle weakness. In LEMS, the body’s own immune system attacks connections between nerves and muscles and disrupts the ability of nerve cells to send signals to muscle cells. Amifampridine blocks voltage-dependent potassium channels, thereby prolonging pre-synaptic cell membrane depolarization. Prolonging the action potential enhances the transport of calcium into the nerve ending. The resulting increase in intracellular calcium concentrations facilitates exocytosis of acetylcholine containing vesicles, which in turn enhances neuromuscular transmission. Amifampridine phosphate has been granted Orphan Drug Designation and Breakthrough Therapy designation by the FDA for the treatment of Lambert-Eaton Myasthenic Syndrome (LEMS).

CNS Activity

Curator's Comment: Amifampridine (3,4-DAP) displays toxicity largely due to blood-brain-barrier (BBB) penetration.

Approval Year

TargetsConditions

Conditions

ConditionModalityTargetsHighest PhaseProduct
Palliative
Firdapse

Approved Use

Symptomatic treatment of Lambert-Eaton myasthenic syndrome (LEMS) in adults.

Launch Date

2009
Cmax

Cmax

ValueDoseCo-administeredAnalytePopulation
40.6 ng/mL
20 mg single, oral
dose: 20 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
AMIFAMPRIDINE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: FEMALE / MALE
food status: FED
59.1 ng/mL
20 mg single, oral
dose: 20 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
AMIFAMPRIDINE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: FEMALE / MALE
food status: FASTED
189 ng/mL
20 mg single, oral
dose: 20 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
3-N-ACETYL-AMIFAMPRIDINE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: FEMALE / MALE
food status: FED
268 ng/mL
20 mg single, oral
dose: 20 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
3-N-ACETYL-AMIFAMPRIDINE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: FEMALE / MALE
food status: FASTED
AUC

AUC

ValueDoseCo-administeredAnalytePopulation
109 ng × h/mL
20 mg single, oral
dose: 20 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
AMIFAMPRIDINE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: FEMALE / MALE
food status: FED
117 ng × h/mL
20 mg single, oral
dose: 20 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
AMIFAMPRIDINE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: FEMALE / MALE
food status: FASTED
1220 ng × h/mL
20 mg single, oral
dose: 20 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
3-N-ACETYL-AMIFAMPRIDINE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: FEMALE / MALE
food status: FED
1444 ng × h/mL
20 mg single, oral
dose: 20 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
3-N-ACETYL-AMIFAMPRIDINE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: FEMALE / MALE
food status: FASTED
T1/2

T1/2

ValueDoseCo-administeredAnalytePopulation
2.28 h
20 mg single, oral
dose: 20 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
AMIFAMPRIDINE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: FEMALE / MALE
food status: FED
2.5 h
20 mg single, oral
dose: 20 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
AMIFAMPRIDINE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: FEMALE / MALE
food status: FASTED
4.03 h
20 mg single, oral
dose: 20 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
3-N-ACETYL-AMIFAMPRIDINE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: FEMALE / MALE
food status: FED
4.1 h
20 mg single, oral
dose: 20 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
3-N-ACETYL-AMIFAMPRIDINE plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: FEMALE / MALE
food status: FASTED
Doses

Doses

DosePopulationAdverse events​
100 mg 1 times / day multiple, oral
Highest studied dose
Dose: 100 mg, 1 times / day
Route: oral
Route: multiple
Dose: 100 mg, 1 times / day
Sources:
unhealthy, adult
10 mg 3 times / day multiple, oral
Recommended
Dose: 10 mg, 3 times / day
Route: oral
Route: multiple
Dose: 10 mg, 3 times / day
Sources:
healthy, adult
Other AEs: Paresthesia, Dysesthesia...
Other AEs:
Paresthesia (69%)
Dysesthesia (69%)
Oral dysesthesia (69%)
Abdominal pain (25%)
Upper abdominal pain (25%)
Dyspepsia (17%)
Dizziness (12%)
Nausea (10%)
Back pain (8%)
Hypoesthesia (6%)
Muscle spasms (6%)
Sources:
75 mg 1 times / day multiple, oral
Studied dose
Dose: 75 mg, 1 times / day
Route: oral
Route: multiple
Dose: 75 mg, 1 times / day
Sources:
unhealthy, adult
Health Status: unhealthy
Age Group: adult
Sex: M+F
Sources:
Other AEs: Convulsion, Head titubation...
Other AEs:
Convulsion (0.6%)
Head titubation (0.6%)
Tremor (0.6%)
Unresponsive to stimuli (0.6%)
Small cell lung cancer (0.6%)
Metastases to central nervous system (0.6%)
Lung cancer metastatic (0.6%)
Pulmonary mass (0.6%)
Bradycardia (0.6%)
Pneumonia (0.6%)
Sources:
AEs

AEs

AESignificanceDosePopulation
Nausea 10%
10 mg 3 times / day multiple, oral
Recommended
Dose: 10 mg, 3 times / day
Route: oral
Route: multiple
Dose: 10 mg, 3 times / day
Sources:
healthy, adult
Dizziness 12%
10 mg 3 times / day multiple, oral
Recommended
Dose: 10 mg, 3 times / day
Route: oral
Route: multiple
Dose: 10 mg, 3 times / day
Sources:
healthy, adult
Dyspepsia 17%
10 mg 3 times / day multiple, oral
Recommended
Dose: 10 mg, 3 times / day
Route: oral
Route: multiple
Dose: 10 mg, 3 times / day
Sources:
healthy, adult
Abdominal pain 25%
10 mg 3 times / day multiple, oral
Recommended
Dose: 10 mg, 3 times / day
Route: oral
Route: multiple
Dose: 10 mg, 3 times / day
Sources:
healthy, adult
Upper abdominal pain 25%
10 mg 3 times / day multiple, oral
Recommended
Dose: 10 mg, 3 times / day
Route: oral
Route: multiple
Dose: 10 mg, 3 times / day
Sources:
healthy, adult
Hypoesthesia 6%
10 mg 3 times / day multiple, oral
Recommended
Dose: 10 mg, 3 times / day
Route: oral
Route: multiple
Dose: 10 mg, 3 times / day
Sources:
healthy, adult
Muscle spasms 6%
10 mg 3 times / day multiple, oral
Recommended
Dose: 10 mg, 3 times / day
Route: oral
Route: multiple
Dose: 10 mg, 3 times / day
Sources:
healthy, adult
Dysesthesia 69%
10 mg 3 times / day multiple, oral
Recommended
Dose: 10 mg, 3 times / day
Route: oral
Route: multiple
Dose: 10 mg, 3 times / day
Sources:
healthy, adult
Oral dysesthesia 69%
10 mg 3 times / day multiple, oral
Recommended
Dose: 10 mg, 3 times / day
Route: oral
Route: multiple
Dose: 10 mg, 3 times / day
Sources:
healthy, adult
Paresthesia 69%
10 mg 3 times / day multiple, oral
Recommended
Dose: 10 mg, 3 times / day
Route: oral
Route: multiple
Dose: 10 mg, 3 times / day
Sources:
healthy, adult
Back pain 8%
10 mg 3 times / day multiple, oral
Recommended
Dose: 10 mg, 3 times / day
Route: oral
Route: multiple
Dose: 10 mg, 3 times / day
Sources:
healthy, adult
Bradycardia 0.6%
75 mg 1 times / day multiple, oral
Studied dose
Dose: 75 mg, 1 times / day
Route: oral
Route: multiple
Dose: 75 mg, 1 times / day
Sources:
unhealthy, adult
Health Status: unhealthy
Age Group: adult
Sex: M+F
Sources:
Convulsion 0.6%
75 mg 1 times / day multiple, oral
Studied dose
Dose: 75 mg, 1 times / day
Route: oral
Route: multiple
Dose: 75 mg, 1 times / day
Sources:
unhealthy, adult
Health Status: unhealthy
Age Group: adult
Sex: M+F
Sources:
Head titubation 0.6%
75 mg 1 times / day multiple, oral
Studied dose
Dose: 75 mg, 1 times / day
Route: oral
Route: multiple
Dose: 75 mg, 1 times / day
Sources:
unhealthy, adult
Health Status: unhealthy
Age Group: adult
Sex: M+F
Sources:
Lung cancer metastatic 0.6%
75 mg 1 times / day multiple, oral
Studied dose
Dose: 75 mg, 1 times / day
Route: oral
Route: multiple
Dose: 75 mg, 1 times / day
Sources:
unhealthy, adult
Health Status: unhealthy
Age Group: adult
Sex: M+F
Sources:
Metastases to central nervous system 0.6%
75 mg 1 times / day multiple, oral
Studied dose
Dose: 75 mg, 1 times / day
Route: oral
Route: multiple
Dose: 75 mg, 1 times / day
Sources:
unhealthy, adult
Health Status: unhealthy
Age Group: adult
Sex: M+F
Sources:
Pneumonia 0.6%
75 mg 1 times / day multiple, oral
Studied dose
Dose: 75 mg, 1 times / day
Route: oral
Route: multiple
Dose: 75 mg, 1 times / day
Sources:
unhealthy, adult
Health Status: unhealthy
Age Group: adult
Sex: M+F
Sources:
Pulmonary mass 0.6%
75 mg 1 times / day multiple, oral
Studied dose
Dose: 75 mg, 1 times / day
Route: oral
Route: multiple
Dose: 75 mg, 1 times / day
Sources:
unhealthy, adult
Health Status: unhealthy
Age Group: adult
Sex: M+F
Sources:
Small cell lung cancer 0.6%
75 mg 1 times / day multiple, oral
Studied dose
Dose: 75 mg, 1 times / day
Route: oral
Route: multiple
Dose: 75 mg, 1 times / day
Sources:
unhealthy, adult
Health Status: unhealthy
Age Group: adult
Sex: M+F
Sources:
Tremor 0.6%
75 mg 1 times / day multiple, oral
Studied dose
Dose: 75 mg, 1 times / day
Route: oral
Route: multiple
Dose: 75 mg, 1 times / day
Sources:
unhealthy, adult
Health Status: unhealthy
Age Group: adult
Sex: M+F
Sources:
Unresponsive to stimuli 0.6%
75 mg 1 times / day multiple, oral
Studied dose
Dose: 75 mg, 1 times / day
Route: oral
Route: multiple
Dose: 75 mg, 1 times / day
Sources:
unhealthy, adult
Health Status: unhealthy
Age Group: adult
Sex: M+F
Sources:
OverviewDrug as perpetrator​

Drug as perpetrator​

TargetModalityActivityMetaboliteClinical evidence
no [Inhibition 30 uM]
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
yes [IC50 490.9 uM]
yes [IC50 524.8 uM]
yes
yes
yes
Drug as victimTox targets
Sourcing

Sourcing

Vendor/AggregatorIDURL
PubMed

PubMed

TitleDatePubMed
3,4-diaminopyridine safety in clinical practice: an observational, retrospective cohort study.
2010-06
Quantification of 4-aminopyridine in plasma by capillary electrophoresis with electrokinetic injection.
2010-02-01
Gold and silver nanoparticles conjugated with heparin derivative possess anti-angiogenesis properties.
2009-11-11
3,4-Diaminopyridine is more effective than placebo in a randomized, double-blind, cross-over drug study in LEMS.
2009-11
Management of myasthenic conditions: nonimmune issues.
2009-10
Skeletal muscle contraction-induced vasodilator complement production is dependent on stimulus and contraction frequency.
2009-07
Efficacy of 3,4-diaminopyridine and pyridostigmine in the treatment of Lambert-Eaton myasthenic syndrome: a randomized, double-blind, placebo-controlled, crossover study.
2009-07
Mutations in LAMB2 causing a severe form of synaptic congenital myasthenic syndrome.
2009-03
[A case of Lambert-Eaton myasthenic syndrome with small cell lung cancer, treated with 3,4-diaminopyridine].
2009-01
[Treatment approach to congenital myasthenic syndrome in a patient with acetylcholine receptor deficiency].
2009-01
Long-lasting in vivo inotropic effects of the K(+) channel blocker 3,4-diaminopyridine during fatigue-inducing stimulation.
2008-12
[Pharmacotherapy of central oculomotor disorders].
2008-12
Therapeutic strategies in congenital myasthenic syndromes.
2008-10
Lambert-Eaton myasthenic syndrome: search for alternative autoimmune targets and possible compensatory mechanisms based on presynaptic calcium homeostasis.
2008-09-15
Brain structural and functional abnormalities in mood disorders: implications for neurocircuitry models of depression.
2008-09
Autoantibodies in neuromuscular transmission disorders.
2008-07
Onset dynamics of type A botulinum neurotoxin-induced paralysis.
2008-06
Mechanisms of neuromodulation as dissected using Sr2+ at motor nerve endings.
2008-06
L-type Ca2+ channel function is linked to dystrophin expression in mammalian muscle.
2008-03-12
Inotropic effects of the K+ channel blocker 3,4-diaminopyridine on fatigued diaphragm muscle.
2008-01-01
[Lambert-Eaton Myasthenic Syndrome associated with vocal cord carcinoma].
2008-01
[Treatment of Lambert-Eaton syndrome with 3,4- diaminopyridine and pyridostigmine].
2007-12-07
[Successful treatment of a Lambert-Eaton myasthenic syndrome patient with 3,4-diaminopyridine].
2007-08-10
Childhood myasthenia: clinical subtypes and practical management.
2007-08
Beneficial effects of 3,4-diaminopyridine on positioning downbeat nystagmus in a circumscribed uvulo-nodular lesion.
2007-08
Myasthenia gravis and Lambert-Eaton myasthenic syndrome in the same patient.
2007-07
Potassium initiates vasodilatation induced by a single skeletal muscle contraction in hamster cremaster muscle.
2007-06-01
Neuromuscular paralysis and recovery in mice injected with botulinum neurotoxins A and C.
2007-05
Molecular docking study of the binding of aminopyridines within the K+ channel.
2007-05
The therapy of congenital myasthenic syndromes.
2007-04
Stability studies of ionised and non-ionised 3,4-diaminopyridine: hypothesis of degradation pathways and chemical structure of degradation products.
2007-01-04
Inotropic effects of the K+ channel blocker 3,4-diaminopyridine: differential responses of rat soleus and extensor digitorum longus.
2006-12
Altered diaphragm muscle action potentials in Zucker diabetic fatty (ZDF) rats.
2006-09-28
Treatment of the gravity dependence of downbeat nystagmus with 3,4-diaminopyridine.
2006-09-12
Extrusion of Ca2+ from mouse motor terminal mitochondria via a Na+-Ca2+ exchanger increases post-tetanic evoked release.
2006-08-01
Pre- and post-synaptic abnormalities associated with impaired neuromuscular transmission in a group of patients with 'limb-girdle myasthenia'.
2006-08
Guidelines for the treatment of autoimmune neuromuscular transmission disorders.
2006-07
Available treatment options for the management of Lambert-Eaton myasthenic syndrome.
2006-07
Potassium channel blockers in multiple sclerosis: neuronal Kv channels and effects of symptomatic treatment.
2006-07
No benefit of 3,4-diaminopyridine in essential tremor: a placebo-controlled crossover study.
2006-06-13
The effects of presynaptic calcium channel modulation by roscovitine on transmitter release at the adult frog neuromuscular junction.
2006-06
Fetal exposure to 3,4-diaminopyridine in a pregnant woman with congenital myasthenia syndrome.
2006-04
[Pathophysiology and treatment of fatigue in multiple sclerosis].
2006-03
[Fatigue and episodic exhaustion as a feature of multiple sclerosis].
2006-03
NCAM 180 acting via a conserved C-terminal domain and MLCK is essential for effective transmission with repetitive stimulation.
2005-06-16
Taicatoxin inhibits the calcium-dependent slow motility of mammalian outer hair cells.
2005-05
Treatment for Lambert-Eaton myasthenic syndrome.
2005-04-18
Effect of 3,4-diaminopyridine on the postural control in patients with downbeat nystagmus.
2005-04
Cognitive deficits in aged rats correlate with levels of L-arginine, not with nNOS expression or 3,4-DAP-evoked transmitter release in the frontoparietal cortex.
2005-03
[Lambert-Eaton myasthenic syndrome: diagnosis and treatment].
2001-11
Patents

Sample Use Guides

Amifampridine (Firdapse) should be given in divided doses, three or four times a day. The recommended starting dose is 15 mg a day, which can be increased in 5 mg increments every 4 to 5 days, to a maximum of 60 mg per day. No single dose should exceed 20 mg. Tablets are to be taken with food. For oral use only.
Route of Administration: Oral
In Vitro Use Guide
In nerve terminal regions of axons in rat olfactory cortex in the presence of tetraethylammonium (TEA, 5 mM) and Cd2+ (100 uM), the K(+)-component was depressed by Amifampridine (3,4-DAP; 1 to 20 uM; IC50 2.0 +/- 0.4 uM).
Name Type Language
FIRDAPSE
Preferred Name English
AMIFAMPRIDINE PHOSPHATE
EMA EPAR   MART.   MI   USAN   WHO-DD  
USAN  
Official Name English
Amifampridine phosphate [WHO-DD]
Common Name English
3,4-DIAMINOPYRIDINE PHOSPHATE
Systematic Name English
AMIFAMPRIDINE PHOSPHATE [MI]
Common Name English
ZENAS
Brand Name English
3,4-DAPP
Code English
AMIFAMPRIDINE PHOSPHATE [MART.]
Common Name English
AMIFAMPRIDINE PHOSPHATE [EMA EPAR]
Common Name English
AMIFAMPRIDINE PHOSPHATE [USAN]
Common Name English
AMIFAMPRIDINE PHOSPHATE [ORANGE BOOK]
Common Name English
DAPP
Code English
3,4-PYRIDINEDIAMINE, PHOSPHATE (1:1)
Systematic Name English
Classification Tree Code System Code
EMA ASSESSMENT REPORTS FIRDAPSE (AUTHORIZED: LAMBERT-EATON MYASTHENIC SYNDROME)
Created by admin on Mon Mar 31 21:07:54 GMT 2025 , Edited by admin on Mon Mar 31 21:07:54 GMT 2025
FDA ORPHAN DRUG 464814
Created by admin on Mon Mar 31 21:07:54 GMT 2025 , Edited by admin on Mon Mar 31 21:07:54 GMT 2025
NCI_THESAURUS C93038
Created by admin on Mon Mar 31 21:07:54 GMT 2025 , Edited by admin on Mon Mar 31 21:07:54 GMT 2025
FDA ORPHAN DRUG 534916
Created by admin on Mon Mar 31 21:07:54 GMT 2025 , Edited by admin on Mon Mar 31 21:07:54 GMT 2025
EU-Orphan Drug EU/3/02/124
Created by admin on Mon Mar 31 21:07:54 GMT 2025 , Edited by admin on Mon Mar 31 21:07:54 GMT 2025
FDA ORPHAN DRUG 295309
Created by admin on Mon Mar 31 21:07:54 GMT 2025 , Edited by admin on Mon Mar 31 21:07:54 GMT 2025
Code System Code Type Description
DRUG BANK
DBSALT002818
Created by admin on Mon Mar 31 21:07:54 GMT 2025 , Edited by admin on Mon Mar 31 21:07:54 GMT 2025
PRIMARY
FDA UNII
8HF8FIN815
Created by admin on Mon Mar 31 21:07:54 GMT 2025 , Edited by admin on Mon Mar 31 21:07:54 GMT 2025
PRIMARY
EVMPD
SUB30951
Created by admin on Mon Mar 31 21:07:54 GMT 2025 , Edited by admin on Mon Mar 31 21:07:54 GMT 2025
PRIMARY
RXCUI
2106337
Created by admin on Mon Mar 31 21:07:54 GMT 2025 , Edited by admin on Mon Mar 31 21:07:54 GMT 2025
PRIMARY
EPA CompTox
DTXSID40196254
Created by admin on Mon Mar 31 21:07:54 GMT 2025 , Edited by admin on Mon Mar 31 21:07:54 GMT 2025
PRIMARY
SMS_ID
100000115908
Created by admin on Mon Mar 31 21:07:54 GMT 2025 , Edited by admin on Mon Mar 31 21:07:54 GMT 2025
PRIMARY
NCI_THESAURUS
C142921
Created by admin on Mon Mar 31 21:07:54 GMT 2025 , Edited by admin on Mon Mar 31 21:07:54 GMT 2025
PRIMARY
MERCK INDEX
m1668
Created by admin on Mon Mar 31 21:07:54 GMT 2025 , Edited by admin on Mon Mar 31 21:07:54 GMT 2025
PRIMARY Merck Index
DAILYMED
8HF8FIN815
Created by admin on Mon Mar 31 21:07:54 GMT 2025 , Edited by admin on Mon Mar 31 21:07:54 GMT 2025
PRIMARY
PUBCHEM
9920716
Created by admin on Mon Mar 31 21:07:54 GMT 2025 , Edited by admin on Mon Mar 31 21:07:54 GMT 2025
PRIMARY
CAS
446254-47-3
Created by admin on Mon Mar 31 21:07:54 GMT 2025 , Edited by admin on Mon Mar 31 21:07:54 GMT 2025
PRIMARY
USAN
BC-58
Created by admin on Mon Mar 31 21:07:54 GMT 2025 , Edited by admin on Mon Mar 31 21:07:54 GMT 2025
PRIMARY
ChEMBL
CHEMBL354077
Created by admin on Mon Mar 31 21:07:54 GMT 2025 , Edited by admin on Mon Mar 31 21:07:54 GMT 2025
PRIMARY