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2D Structure
Also known as: 504-24-5, Pyridin-4-amine, Fampridine, 4-pyridinamine, Dalfampridine, 4-pyridylamine
Molecular Formula
C5H6N2
Molecular Weight
94.11  g/mol
InChI Key
NUKYPUAOHBNCPY-UHFFFAOYSA-N
FDA UNII
BH3B64OKL9

One of the POTASSIUM CHANNEL BLOCKERS with secondary effect on calcium currents which is used mainly as a research tool and to characterize channel subtypes.
Dalfampridine is a Potassium Channel Blocker. The mechanism of action of dalfampridine is as a Potassium Channel Antagonist.
1 2D Structure

2D Structure

2 Identification
2.1 Computed Descriptors
2.1.1 IUPAC Name
pyridin-4-amine
2.1.2 InChI
InChI=1S/C5H6N2/c6-5-1-3-7-4-2-5/h1-4H,(H2,6,7)
2.1.3 InChI Key
NUKYPUAOHBNCPY-UHFFFAOYSA-N
2.1.4 Canonical SMILES
C1=CN=CC=C1N
2.2 Other Identifiers
2.2.1 UNII
BH3B64OKL9
2.3 Synonyms
2.3.1 MeSH Synonyms

1. 4 Aminopyridine

2. 4 Aminopyridine Sustained Release

3. 4-aminopyridine Sustained Release

4. Dalfampridine

5. Fampridine Sr

6. Fampridine-sr

7. Pymadine

8. Sustained Release, 4-aminopyridine

9. Vmi 103

10. Vmi-103

11. Vmi103

2.3.2 Depositor-Supplied Synonyms

1. 504-24-5

2. Pyridin-4-amine

3. Fampridine

4. 4-pyridinamine

5. Dalfampridine

6. 4-pyridylamine

7. P-aminopyridine

8. 4-ap

9. Avitrol

10. Ampyra

11. Gamma-aminopyridine

12. Avitrol 200

13. Pyridine, 4-amino-

14. Amino-4 Pyridine

15. Fampyra

16. Pimadin (free Base)

17. Compound 1861

18. Phillips 1861

19. Neurelan

20. Amaya

21. Prc 1237

22. Vmi 10-3

23. El-970

24. 4-amino-pyridine

25. 4- Aminopyridine

26. Pyridin-4-ylamine

27. Nsc 15041

28. Fampridine [inn]

29. .gamma.-aminopyridine

30. Dalfampridine [usan]

31. 4-aminopyrdine

32. N07xx07

33. Nsc-15041

34. Bh3b64okl9

35. Mls000069400

36. Chembl284348

37. Dalfampridine (4-aminopyridine)

38. Chebi:34385

39. 4-pyridinamine, Labeled With Deuterium

40. Dalfampridine (usan)

41. Ncgc00015009-08

42. Smr000058211

43. 4 Aminopyridine

44. Fampridine-sr

45. Dsstox_cid_3870

46. Dsstox_rid_77212

47. Dsstox_gsid_23870

48. Caswell No. 038

49. C5h6n2

50. Vmi-103

51. 4-amino Pyridine

52. Mi-w-3

53. 4ap

54. 916979-36-7

55. Cas-504-24-5

56. Ampyra (tn)

57. Hsdb 6037

58. Vmi 103

59. Sr-01000075299

60. Einecs 207-987-9

61. Rcra Waste No. P008

62. Unii-bh3b64okl9

63. Epa Pesticide Chemical Code 069201

64. Dalfampridine [usan:inn]

65. Brn 0105782

66. Fampridina

67. Fampridinum

68. Frampridine

69. Ampydin

70. Biib041

71. Pymadin

72. Ai3-52547

73. Biib 041

74. Fampridine-pr

75. Dalfampridine-er

76. 4-pyridyl Amine

77. Para-aminopyridine

78. Pyridine-4-amine

79. 3rxf

80. Neurelan (tn)

81. Pyridine-4-ylamine

82. Fampyra (tn)

83. Pyridin-4-yl-amine

84. Mfcd00006439

85. 4-aminopyridine 10

86. Philips 1861

87. Spectrum_000155

88. Tocris-0940

89. Fampridine (jan/inn)

90. 4-aminopyridine, 98%

91. Fampridine [jan]

92. Pyridine,4-amino

93. Opera_id_1768

94. Spectrum2_001413

95. Spectrum3_000914

96. Spectrum4_001013

97. Spectrum5_001501

98. Lopac-a-0152

99. Dalfampridine [ii]

100. Dalfampridine [mi]

101. Fampridine [vandf]

102. Upcmld-dp125

103. Wln: T6nj Dz

104. 4-aminopyridine (4-ap)

105. Fampridine [mart.]

106. 4-aminopyridine, >=99%

107. Dalfampridine [hsdb]

108. Fampridine [who-dd]

109. 1,4-dihydropyridin-4-imine

110. Lopac0_000032

111. Bspbio_001562

112. Dalfampridine [vandf]

113. Fampridine (4-aminopyridine)

114. Kbiogr_000282

115. Kbiogr_001505

116. Kbioss_000282

117. Kbioss_000635

118. 4-imino-1,4-dihydropyridine

119. 5-22-09-00106 (beilstein Handbook Reference)

120. Divk1c_000572

121. Fampridine [ema Epar]

122. Spectrum1501130

123. Spbio_001486

124. Dalfampridine [usp-rs]

125. 4 Ap

126. Biib-041

127. Gtpl2416

128. Cl-cob-iii-274-1

129. Dtxsid0023870

130. Upcmld-dp125:001

131. Ampd00207

132. Bdbm10458

133. Hms501m14

134. Kbio1_000572

135. Kbio2_000282

136. Kbio2_000635

137. Kbio2_002850

138. Kbio2_003203

139. Kbio2_005418

140. Kbio2_005771

141. Kbio3_000563

142. Kbio3_000564

143. Kbio3_001888

144. Ninds_000572

145. Bio1_000353

146. Bio1_000842

147. Bio1_001331

148. Bio2_000282

149. Bio2_000762

150. Hms1361o04

151. Hms1791o04

152. Hms1921h15

153. Hms1989o04

154. Hms2092f05

155. Hms2234n24

156. Hms3260g05

157. Hms3267e21

158. Hms3370j03

159. Hms3402o04

160. Hms3414h15

161. Hms3678h13

162. Hms3886i09

163. Kuc111877n

164. Pharmakon1600-01501130

165. Zinc599985

166. Dalfampridine [orange Book]

167. Act05167

168. Hy-b0604

169. Nsc15041

170. Vmi-10-3

171. Tox21_110065

172. Tox21_200793

173. Tox21_500032

174. Ccg-39031

175. Dalfampridine [usp Monograph]

176. Nsc757845

177. Rb8003

178. S5028

179. Stk298717

180. Akos000119896

181. Tox21_110065_1

182. Bs-3729

183. Db06637

184. Lp00032

185. Nsc-757845

186. Sdccgmls-0066228.p001

187. Sdccgsbi-0050021.p004

188. Idi1_000572

189. Idi1_034032

190. P-aminopyridine [un2671] [poison]

191. Ncgc00015009-01

192. Ncgc00015009-02

193. Ncgc00015009-03

194. Ncgc00015009-04

195. Ncgc00015009-05

196. Ncgc00015009-06

197. Ncgc00015009-07

198. Ncgc00015009-09

199. Ncgc00015009-10

200. Ncgc00015009-11

201. Ncgc00015009-12

202. Ncgc00015009-13

203. Ncgc00015009-14

204. Ncgc00015009-16

205. Ncgc00015009-23

206. Ncgc00015009-24

207. Ncgc00024890-01

208. Ncgc00024890-02

209. Ncgc00024890-03

210. Ncgc00024890-04

211. Ncgc00024890-05

212. Ncgc00024890-06

213. Ncgc00024890-07

214. Ncgc00024890-08

215. Ncgc00024890-09

216. Ncgc00024890-10

217. Ncgc00258347-01

218. Ncgc00260717-01

219. Bp-21343

220. Sbi-0050021.p003

221. Db-028705

222. A0414

223. Am20061261

224. B3530

225. Eu-0100032

226. Ft-0665455

227. Fampridine (4-aminopyridine) [vandf]

228. A 0152

229. D04127

230. Ab00052209_12

231. [j.pharmacol.exp.ther. 275:864 (1995)]

232. Ac-907/25014071

233. Q372539

234. 4-aminopyridine, Pestanal(r), Analytical Standard

235. Q-200436

236. Sr-01000075299-1

237. Sr-01000075299-3

238. Sr-01000075299-5

239. F2190-0487

240. Z955123498

241. Methyl3,5-dibromo-2,4-dihydroxy-6-methylbenzoate

242. Dalfampridine, United States Pharmacopeia (usp) Reference Standard

2.4 Create Date
2005-03-25
3 Chemical and Physical Properties
Molecular Weight 94.11 g/mol
Molecular Formula C5H6N2
XLogP30.3
Hydrogen Bond Donor Count1
Hydrogen Bond Acceptor Count2
Rotatable Bond Count0
Exact Mass94.053098200 g/mol
Monoisotopic Mass94.053098200 g/mol
Topological Polar Surface Area38.9 Ų
Heavy Atom Count7
Formal Charge0
Complexity48
Isotope Atom Count0
Defined Atom Stereocenter Count0
Undefined Atom Stereocenter Count0
Defined Bond Stereocenter Count0
Undefined Bond Stereocenter Count0
Covalently Bonded Unit Count1
4 Drug and Medication Information
4.1 Drug Information
1 of 2  
Drug NameAmpyra
PubMed HealthDalfampridine (By mouth)
Drug ClassesCentral Nervous System Agent
Active IngredientDalfampridine
Dosage FormTablet, extended release
RouteOral
Strength10mg
Market StatusPrescription
CompanyAcorda

2 of 2  
Drug NameAmpyra
PubMed HealthDalfampridine (By mouth)
Drug ClassesCentral Nervous System Agent
Active IngredientDalfampridine
Dosage FormTablet, extended release
RouteOral
Strength10mg
Market StatusPrescription
CompanyAcorda

4.2 Therapeutic Uses

Potassium Channel Blockers

National Library of Medicine's Medical Subject Headings. 4-Aminopyridine. Online file (MeSH, 2014). Available from, as of March 24, 2014: https://www.nlm.nih.gov/mesh/2014/mesh_browser/MBrowser.html


Ampyra (dalfampridine) is a potassium channel blocker indicated to improve walking in patients with multiple sclerosis (MS). /Included in US product label/

US Natl Inst Health; DailyMed. Current Medication Information for AMPYRA (dalfampridine) tablet, film coated, extended release (January 2014). Available from, as of March 25, 2014: https://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=550eb76a-e4a6-4fa1-ad65-c0fd8b0ce783


Distribution of dalfampridine is restricted; the drug is available only through certain specialty pharmacies.

American Society of Health-System Pharmacists 2013; Drug Information 2013. Bethesda, MD. 2013, p. 3780


4.3 Drug Warning

Anaphylactic reactions have been reported rarely in patients receiving dalfampridine. If an anaphylactic or other serious allergic reaction occurs, dalfampridine should be discontinued and should not be restarted.

American Society of Health-System Pharmacists 2013; Drug Information 2013. Bethesda, MD. 2013, p. 3778


Dalfampridine can cause seizures. Postmarketing reports indicate that the majority of seizures have occurred in patients receiving the recommended dalfampridine dosage (generally within days to weeks after starting the drug) and in patients without a history of seizures. Some patients had been receiving other drugs that could have increased the risk of seizures or lowered the seizure threshold; in addition, age-related renal dysfunction and resultant increases in plasma dalfampridine concentrations could have contributed to the risk of seizures. Use of a high dalfampridine dosage (e.g., 15 or 20 mg twice daily) increases the risk of seizures. In open-label extension studies in patients with multiple sclerosis (MS), the incidence of seizures was more than 4 times greater at a dosage of 15 mg twice daily compared with that reported with the recommended dosage (10 mg twice daily).

American Society of Health-System Pharmacists 2013; Drug Information 2013. Bethesda, MD. 2013, p. 3778


Dalfampridine is contraindicated in patients with a prior history of seizures. The drug has not been evaluated in patients with a history of seizures or with evidence of epileptiform activity on EEG; such patients were excluded from clinical trials. The risk of seizures in patients with epileptiform activity on EEG is unknown and could be substantially higher than that observed in clinical trials.

American Society of Health-System Pharmacists 2013; Drug Information 2013. Bethesda, MD. 2013, p. 3778


Urinary tract infections (UTIs) have been reported more frequently in patients receiving dalfampridine (12%) than in patients receiving placebo (8%). If a UTI occurs in a patient receiving dalfampridine, it should be evaluated and treated as clinically indicated.

American Society of Health-System Pharmacists 2013; Drug Information 2013. Bethesda, MD. 2013, p. 3778


For more Drug Warnings (Complete) data for 4-AMINOPYRIDINE (12 total), please visit the HSDB record page.


4.4 Drug Indication

Dalfampridine is a neurofunctional modifier that helps improve walking speed in patients with multiple sclerosis (MS).


FDA Label


Fampyra is indicated for the improvement of walking in adult patients with multiple sclerosis with walking disability (Expanded Disability Status Scale 4-7).


Multiple sclerosis with walking disability


Fampridine Accord is indicated for the improvement of walking in adult patients with multiple sclerosis with walking disability (EDSS 4-7).


5 Pharmacology and Biochemistry
5.1 Pharmacology

Dalfampridine is a board-spectrum lipophillic potassium channel blocker and binds favourably to the open state than closed state of the potassium channel in the CNS. Its pharmacological target are the potassium channels exposed in MS patients. Does not prolong the QTc interval.


5.2 MeSH Pharmacological Classification

Potassium Channel Blockers

A class of drugs that act by inhibition of potassium efflux through cell membranes. Blockade of potassium channels prolongs the duration of ACTION POTENTIALS. They are used as ANTI-ARRHYTHMIA AGENTS and VASODILATOR AGENTS. (See all compounds classified as Potassium Channel Blockers.)


5.3 FDA Pharmacological Classification
5.3.1 Active Moiety
DALFAMPRIDINE
5.3.2 FDA UNII
BH3B64OKL9
5.3.3 Pharmacological Classes
Potassium Channel Blocker [EPC]; Potassium Channel Antagonists [MoA]
5.4 ATC Code

N07XX07


N07XX07


N07XX07

S76 | LUXPHARMA | Pharmaceuticals Marketed in Luxembourg | Pharmaceuticals marketed in Luxembourg, as published by d'Gesondheetskeess (CNS, la caisse nationale de sante, www.cns.lu), mapped by name to structures using CompTox by R. Singh et al. (in prep.). List downloaded from https://cns.public.lu/en/legislations/textes-coordonnes/liste-med-comm.html. Dataset DOI:10.5281/zenodo.4587355


N - Nervous system

N07 - Other nervous system drugs

N07X - Other nervous system drugs

N07XX - Other nervous system drugs

N07XX07 - Fampridine


5.5 Absorption, Distribution and Excretion

Absorption

Orally-administered dalfampridine is rapidly and completely absorbed from the gastrointestinal tract. Tmax, immediate release form = 1 hour; Tmax, extended release form = 3.5 hours; Cmax, 10 mg extended release = 17.3 - 21.6 ng/mL; Relative bioavailability of 10 mg extended-release tablets compared to aqueous oral solution = 96%


Route of Elimination

Almost all of the dose and its metabolites are completely eliminated by the kidneys after 24 hours. Urine (96%; 90% of total dose as unchanged drug); Feces (0.5%)


Volume of Distribution

10 mg extended release = 2.6 L/kg


Like other aminopyridines, 4-aminopyridine is rapidly absorbed from the gastrointestinal tract into circulation. The compound is readily metabolized in the liver and metabolites are excreted in urine. About 90% of the administered dose, following IV or oral administration, excretes in the urine.

Gupta, R. C. (ed.) Veterinary Toxicology: Basic and Clinical Principles. 1st ed. New York, NY, p.561-2 (2007)


Dalfampridine is rapidly and completely absorbed from the GI tract.

American Society of Health-System Pharmacists 2013; Drug Information 2013. Bethesda, MD. 2013, p. 3779


The bioavailability of dalfampridine extended-release tablets is 96% compared with an extemporaneously prepared aqueous oral solution of immediate-release dalfampridine (formerly known as fampridine (4-aminopyridine, 4-AP)). Dalfampridine extended-release tablets result in delayed absorption and a slower increase to lower peak plasma concentrations compared with an aqueous oral solution of the drug, but the extent of absorption (area under the concentration-time curve (AUC)) is not affected. Plasma concentrations and AUC of dalfampridine increase proportionally with dose.

American Society of Health-System Pharmacists 2013; Drug Information 2013. Bethesda, MD. 2013, p. 3779


The pharmacokinetics of dalfampridine in adults with multiple sclerosis (MS) are similar to that reported in healthy adults. In adults 29-56 years of age with MS who received a single 10-mg dalfampridine extended-release tablet, the mean peak plasma concentration was 25.23 ng/mL and was attained 3.92 hours after the dose. In healthy fasting adults, a single 10-mg extended-release tablet of the drug resulted in peak concentrations of 17.3-21.6 ng/mL and occurred 3-4 hours after the dose.

American Society of Health-System Pharmacists 2013; Drug Information 2013. Bethesda, MD. 2013, p. 3779


For more Absorption, Distribution and Excretion (Complete) data for 4-AMINOPYRIDINE (8 total), please visit the HSDB record page.


5.6 Metabolism/Metabolites

Not extensively metabolized by the liver therefore drugs effecting the cytochrome P450 enzyme system that are concomitantly administered with dalfampridine are not expected to interact with each other. Metabolites include 3-hydroxy-4-aminopyridine and 3-hydroxy-4-aminopyridine sulfate and both are inactive. CYP2E1 is the enzyme responsible for 3-hydroxylation of dalfampridine.


The specific enzymes involved in the metabolism of fampridine were not identified in laboratory animals, but based on human microsome studies; it was suggested that CYP2E1 could be responsible for hydroxylation in man. In rat, approximately 36% of the parent drug was removed by hepatic first-pass metabolism. Fampridine was metabolized primarily by hydroxylation, followed by sulfate conjugation. Two circulating metabolites were detected in mouse, rat, rabbit, dog and human plasma: 3-hydroxy-4-AP and 3-hydroxy-4-AP sulfate. Although these metabolites were identified in all species, more extensive metabolism was determined in rats and dogs than in humans. In mouse and rat plasma, it was demonstrated that 4-AP-N-oxide was also a circulating metabolite. In human plasma, two unidentified metabolites were present; however, these metabolites accounted for <2% of the radioactivity.

European Medicines Agency (EMA), Committee for Medicinal Products for Human Use (CHMP), European Public Assessment Report (EPAR): Fampyra (Fampridine), p.13 (2011). Available from, as of March 27, 2014: https://www.ema.europa.eu/docs/en_GB/document_library/EPAR_-_Public_assessment_report/human/002097/WC500109957.pdf


A small portion of dalfampridine dose is metabolized by cytochrome P-450 (CYP) isoenzymes to 3-hydroxy-4-aminopyridine and 3-hydroxy-4-aminopyridine sulfate. These metabolites have no pharmacologic activity on potassium channels. In vitro studies indicate CYP2E1 is the major enzyme responsible for 3-hydroxylation of dalfampridine; other unidentified CYP enzymes play a minor role in 3-hydroxylation of the drug.

American Society of Health-System Pharmacists 2013; Drug Information 2013. Bethesda, MD. 2013, p. 3779


5.7 Biological Half-Life

Immediate release form = 3.5 hours; Extended release form = 5.47 hours;


Elimination of fampridine was in a similar range between rats and dogs with a plasma half-life of 1-2 hr, but was slightly prolonged in humans.

European Medicines Agency (EMA), Committee for Medicinal Products for Human Use (CHMP), European Public Assessment Report (EPAR): Fampyra (Fampridine), p.13 (2011). Available from, as of March 27, 2014: https://www.ema.europa.eu/docs/en_GB/document_library/EPAR_-_Public_assessment_report/human/002097/WC500109957.pdf


The half-life of dalfampridine is 5.2-6.5 hours. The half-life of 3-hydroxy-4-aminopyridine sulfate is 7.6 hours. /in humans/

American Society of Health-System Pharmacists 2013; Drug Information 2013. Bethesda, MD. 2013, p. 3779


5.8 Mechanism of Action

In MS, axons are progressively demyelinated which exposes potassium channels. As a result, there is a leak of potassium ions which results in the repolarization of cells and a decrease in neuronal excitability. The overall impact is the impairment of neuromuscular transmission as it is harder to trigger an action potential. Dalfampridine inhibits voltage-gated potassium channels in the CNS to maintain the transmembrane potential and prolong action potential. In other words, dalfampridine works to make sure that the current available is high enough to stimulate conduction in demyelinated axons that are exposed in MS patients. Furthermore, it facilitates neuromuscular and synaptic transmission by relieving conduction blocks in demyelinated axons.


Electrophysiological dysfunction of Purkinje cells causes cerebellar ataxia. Recent studies indicated that 4-aminopyridine (4-AP) can prevent the attacks in patients with episodic ataxia type 2. However, the cellular mechanism(s) by which 4-AP might be beneficial for the improvement of motor function remain unclear. Here, electrophysiological and behavioral consequences of in vivo co-treatment with 4-AP against 3-acetylpyridine (3-AP)-induced ataxia in rats were assessed. Combined treatment with 4-AP partially improved motor behavior compared to the ataxic rats. Treatment with 3-AP alone induced plastic alterations in the cells' intrinsic properties, so that the latency of the initial neural spike was significantly increased (Pb 0.001); however, both instantaneous firing frequency and amplitude of calcium spikes were significantly (Pb 0.001) suppressed. 3-AP treatment also resulted in significant decrease in the duration of action potential (Pb 0.05) and the amplitude of after hyperpolarization (Pb 0.05) as well as post-stimulus hyperpolarization potentials (Pb 0.001). Purkinje cells in rats co-treated with 4-AP, however, fired predominantly in rhythmic bursts. The mean amplitude of Ca2+ spikes was significantly (Pb 0.001) greater compared to ataxic rats, but similar to control value. As evidenced by a significant decrease (Pb 0.001) in the first spike latency, the cells' intrinsic excitability was also increased. In 4-AP co-treated group, the duration of action potential was also significantly lengthened (Pb 0.001) compared to control and 3-AP group. These results suggest that modulation of intrinsic electrical properties and potentiation of Ca2+ channels function caused by in vivo 4-AP treatment is likely to be partly responsible for its neuroprotective action.

PMID:20638947 Goudarzi I et al; Eur J Pharmacol 642 (1-3): 56-65 (2010)


4-Aminopyridine enhances the release of acetylcholine pre synaptically, increasing the force of muscle contraction. It antagonizes the neuromuscular blockade produced by many antibiotics. 4-Aminopyridine is relatively free of muscarinic side effects." 4-Aminopyridine readily crosses the blood brain barrier. It may be useful as an antagonist of nondepolarizing neuromuscular blocking agents such as d-tubocurarine, gallamine, pancuronium, atracurium, vecuronium, doxacurium, and pipecuronium.

Ellenhorn, M.J., S. Schonwald, G. Ordog, J. Wasserberger. Ellenhorn's Medical Toxicology: Diagnosis and Treatment of Human Poisoning. 2nd ed. Baltimore, MD: Williams and Wilkins, 1997., p. 957


4-Aminopyridine blocks potassium ion channels and increases acetylcholine (ACh) levels at the synapses and neuromuscular junctions.

Gupta, R. C. (ed.) Veterinary Toxicology: Basic and Clinical Principles. 1st ed. New York, NY, p.562 (2007)


4-Aminopyridine block voltage-dependent potassium channels, producing secondary effects on calcium channels and influx of the cation, and this promotes release of acetylcholine.

Harvey, A.L. (ed.). Natural and Synthetic Neurotoxins. London, England: Academic Press 1993., p. 301


For more Mechanism of Action (Complete) data for 4-AMINOPYRIDINE (11 total), please visit the HSDB record page.