ENABLE

Treatment tested

• Dalfampridine

  Voltage-gated potassium channel blocker

Other measures (35)

Key Inclusion Criteria: * Ability to understand the purpose and risks of the study and provide signed and dated informed consent and authorization to use protected health information in accordance with national and local subject privacy regulations. * Must have a diagnosis of primary-progressive, secondary-progressive, progressive-remitting, or relapsing-remitting multiple sclerosis (MS) per revised McDonald Committee criteria ([Polman et al, 2011]) as defined by Lublin and Reingold [Lublin and Reingold 1996] of at least 3 months duration. * Have a walking impairment as determined by the Investigator. * Able to perform the Timed 25-foot Walk Test with or without a walking aid. * Female subjects of childbearing potential must practice effective contraception during the study and be willing and able to continue contraception for 30 days after their last dose of study treatment. * Able to understand and comply with the requirements of the protocol. Key Exclusion Criteria: * Known allergy to pyridine-containing substances or to any of the inactive ingredients in the prolonged-release fampridine tablet. * Any history of seizure, epilepsy, or other convulsive disorder, with the exception of febrile seizures in childhood. * An estimated creatinine clearance of \<80 mL/minute. * Subject needs to take medicinal products that are inhibitors of organic cation transporter 2 (OCT2 [e.g., cimetidine]). * Female subjects who are currently pregnant or who are considering becoming pregnant while participating in the study. * Female subjects who are currently breastfeeding. * Previous exposure to fampridine. NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.

The primary objective of the study is to assess the effect of long-term treatment with prolonged-release fampridine (BIIB041) 10 mg twice daily on the physical component scale (PCS) of the Short Form 36 Health Status Questionnaire (SF-36) as reported by treatment responders. The secondary objectives of this study are to compare the change in the PCS of the SF-36 between treatment responders and non-responders, to evaluate change from baseline in additional quality of life measures among treatment responders as well as changes from baseline in treatment responders versus non-responders and to assess the safety and tolerability of prolonged-release fampridine 10 mg twice daily.