Effect of fampridine on axonal excitability in multiple sclerosis.
OBJECTIVE
To investigate the effects of fampridine on nerve excitability, the present study utilized peripheral axonal excitability techniques in 18 MS patients receiving treatment with fampridine.


METHODS
Studies were performed at baseline and repeated 3months after institution of fampridine at standard dosing.


RESULTS
Following treatment with fampridine there were significant changes in axonal excitability for those parameters associated with fast K(+) channels that shifted towards normal control values. Specifically, increases were noted in the peak superexcitability of recovery cycle (fampridine, -25.6±1.6%; baseline -22.8±1.7%; p<0.004), peak depolarizing threshold electrotonus (fampridine, 69.1±1.0%; baseline 67.0±1.4%; p<0.004), and depolarizing threshold electrotonus between 40 and 60ms after onset of depolarization (fampridine, 52.8±1.3%; baseline 49.9±1.4%; p=0.02).


CONCLUSIONS
The present study has established that fampridine at standard doses exerts effects on peripheral nerve function that may be mediated by reduction of fast K(+) conductances.


CONCLUSIONS
Modulation of fast K(+) conductances by fampridine may contribute to the improvement observed in MS symptoms including motor fatigue.
Brain and Mind Centre, University of Sydney, New South Wales, Australia; Prince of Wales Clinical School, University of New South Wales, New South Wales, Australia. Electronic address: w.huynh@neura.edu.au.
William
W
Huynh
School of Medical Sciences, University of New South Wales, New South Wales, Australia.
Hannah
H
Pickering
Brain and Mind Centre, University of Sydney, New South Wales, Australia.
James
J
Howells
Prince of Wales Clinical School, University of New South Wales, New South Wales, Australia.
Jenna
J
Murray
Prince of Wales Clinical School, University of New South Wales, New South Wales, Australia.
Christine
C
Cormack
School of Medical Sciences, University of New South Wales, New South Wales, Australia.
Cindy S-Y
CS
Lin
Western Clinical School, University of Sydney, New South Wales, Australia.
Steve
S
Vucic
Brain and Mind Centre, University of Sydney, New South Wales, Australia.
Matthew C
MC
Kiernan
Prince of Wales Clinical School, University of New South Wales, New South Wales, Australia.
Arun V
AV
Krishnan
D015761:4-Aminopyridine / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D000328:Adult; D000368:Aged; D001369:Axons / Q000187:drug effects / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000188:drug therapy*; D009431:Neural Conduction / Q000187:drug effects*; D026902:Potassium Channel Blockers / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*
D026902:Potassium Channel Blockers; D015761:4-Aminopyridine
Fampridine; Ion channel; Multiple sclerosis; Nerve excitability