['multiple sclerosis']
['fampridine', 'placebo']

        Key Inclusion Criteria:

          -  Must have a diagnosis of primary-progressive, secondary-progressive,
             progressive-relapsing, or relapsing-remitting MS per revised McDonald Committee
             criteria [McDonald 2001; Polman 2005] as defined by Lublin and Reingold [Lublin and
             Reingold 1996] of at least 3 months duration

          -  Must have an Expanded Disability Status Scale (EDSS) score of 4 to 7, inclusive

          -  Must have walking impairment, as deemed by the Investigator

        Key Exclusion Criteria:

          -  History of human immunodeficiency virus (HIV)

          -  Presence of acute or chronic hepatitis. Subjects who have evidence of prior hepatitis
             infection that has been serologically confirmed as resolved are not excluded from
             study participation

          -  Known allergy to fampridine, pyridine-containing substances, or any of the inactive
             ingredients in the prolonged-release fampridine tablet

          -  Creatinine clearance (CrCl) of <80 mL/min

          -  History of malignant disease

          -  Presence of pulmonary disease

          -  A body mass index (BMI) ≥40 (BMI formula: BMI = mass [kg]/[height(m)]2)

        NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.
      