A Multicenter, Randomized, Double-Blind, Placebo-Controlled Exploratory Study to Assess the Effect of Treatment With Prolonged-Release Fampridine (BIIB041) 10 mg Twice Daily on Walking Ability and Balance in Subjects with Multiple Sclerosis (MOBILE)

To be eligible to participate in this study, candidates must meet the following eligibility criteria at the Screening Visit or at the timepoint specified in the individual eligibility criterion listed:
1. Ability to understand the purpose and risks of the study and provide signed and dated informed consent and authorization to use protected health information (PHI) in accordance with national and local subject privacy regulations.
2. Male or female subjects must be 18 to 70 years old, inclusive, at the time of informed consent.
3. Must have a diagnosis of primary-progressive, secondary-progressive, progressive-remitting, or relapsingremitting MS per revised McDonald Committee criteria ([McDonald et al, 2001; Polman et al, 2005] as defined by Lublin and Reingold [Lublin and Reingold 1996]; Section 22.2; Appendix B) of at least 3-month duration.
4. EDSS 4 to 7
5. 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. For further details of contraceptive requirements for this study, please refer to Section 15.5.3.
6. Subjects must be able to understand and comply with the requirements of the protocol.

1.Known allergy to pyridine-containing substances or to any of the inactive ingredients in the prolonged-release fampridine tablet.
2.Any history of seizure, epilepsy, or other convulsive disorder, with the exception of febrile seizures in childhood.
3. An estimated CrCl of <80 mL/minute (using the Cockcroft-Gault formula).
4.Known history of Human Immunodeficiency Virus, hepatitis C, or hepatitis B. Subjects who have evidence of prior hepatitis infection that has been serologically confirmed as resolved based on previous testing documented in the subjects* medical history are not excluded from study participation.
5.History of malignant disease including solid tumors and hematologic malignancies (with the exception of basal cell and squamous cell carcinomas of the skin that have been completely excised and are considered cured) within the 5 years prior to the Screening Visit, or at any time during the screening period.
6.Onset of MS exacerbation within the 60 days prior to the Screening Visit, or at any time during the screening period.
7.History of any major surgical intervention (with the exception of skin biopsy) within the 30 days prior to the Screening Visit, or at any time during the screening period.
8.Any non-MS-related condition or factor (as determined by the Investigator) that is likely to interfere with walking ability including, but not limited to, previous major surgery of the foot, leg, or hip; any significant trauma; or known peripheral neuropathy of the lower limb.
9.Presence of pulmonary disease including, but not limited to, chronic obstructive pulmonary disease that could impede the subject*s daily activities (as determined by the Investigator)10.Presence of any psychiatric disorder, including clinical depression, that is likely to interfere with the subject*s participation in the study (as determined by the Investigator).
11.Uncontrolled hypertension (as determined by the Investigator) at the Screening Visit, any time during the screening period, or Day 1.
12.History of any clinically significant endocrinologic, hematologic, immunologic, metabolic, urologic, neurologic (except for MS, but including events indicative of a potentially lower seizure threshold), dermatologic, or other major disease (as determined by the Investigator).
13.Clinically significant abnormal laboratory values (as determined by the Investigator).
14.A Body Mass Index *40.
15. Use of off-label MS treatment including rituximab, alemtuzumab, daclizumab, or antibody (except natalizumab) within the 3 months prior to the Screening Visit, or any time during the screening period, or scheduled use during study participation.
16.Use of mitoxantrone or cyclophosphamide within the 3 months prior to the Screening Visit, or any time during the screening period, or scheduled use during study participation.
17.Initiation of natalizumab treatment or any change in the subject*s dose or regimen of natalizumab, within the 3 months prior to the Screening Visit, or at any time during the screening period.
18. Initiation of treatment with, or any change in the subject*s dose or regimen of, interferon *-1b, interferon *-1a, fingolimod, or glatiramer acetate within the 30 days prior to the Screening Visit, or at any time during the screening period.
19.Pulsed steroid treatment within the 60 days prior to the Screening Visit, or at any time during the screening period.
20.Any change in the subject*s medication dose or regimen for the treatment of fatigue or depression within the 30 days prior to the Screening Visit, or at any time during the screening period.
21. Any change in prophylactic treatment for pain with antidepressants or anticonvulsants prescribed for this purpose within 30 days prior to the Screening Visit, or at any time during the screening period.
22.Any change in the subject*s dose or regimen of antispastic agents within the 7 days prior to the Screening Visit, or at any time during the screening period.
23. Treatment with an investigational drug or approved therapy for investigational use within the 30 days (or 7 half-lives, whichever is longer) prior to the Screening Visit, or at any time during the screening period.
24.Treatment with 4-AP or 3,4-diaminopyridine (DAP) in any formulation within the 30 days prior to the Screening Visit, or at any time during the screening period
25.History of drug or alcohol abuse (as defined by the Investigator) within the 2 years prior to the Screening Visit, or at any time during the screening period.
26.Female subjects who are currently pregnant or who are considering becoming pregnant while participating in the study. Female subjects of childbearing potential who have a positive pregnancy test at either the Screening Visit or Day 1 may not participate in this study
27.Female subjects who are currently breastfeeding.
28.Inability to comply with study requirements.
29.Current enrollment in any other drug, biological, device, or clinical study.
30.Previous participation in this study.
31.Any other reason, in the opinion of the Investigator, which would disqualify the subject from participation in this study or make the subject unsuitable for enrollment