Safety and Efficacy of ADS-5102 in Multiple Sclerosis Patients With Walking Impairment

Inclusion Criteria: * Signed a current IRB-approved informed consent form * Male or female subjects between 18 and 70 years of age, inclusive, at the time of Screening * Confirmed diagnosis of MS according to the 2017 McDonald criteria * Current medication regimen must be stable for at least 30 days prior to screening, and subject must be willing to continue the same dosing regimen for the duration of study participation * Maximum Expanded Disability Status Scale (EDSS) score during screening of 6.5 * Stable physical activity level (inclusive of prescribed physical therapy) for at least 30 days prior to screening and willing to continue without change for the duration of study participation * A score on each of two completed screening T25FW tests between 8 and 45 seconds, inclusive Exclusion Criteria: * Documented inability to tolerate amantadine * Clinically significant MS relapse with onset less than 30 days prior to screening * Receipt of dalfampridine (or any 4-aminopyridine or 2,4-diaminopyridine preparation) or amantadine within 30 days prior to screening * History of seizures within 3 years prior to screening * History of hallucinations (visual, auditory, or any other type) within 3 years prior to screening * History of bipolar disorder, schizophrenia, or psychosis, regardless of treatment * For subjects with a history of major depressive disorder, the presence of active depressive symptoms that, in the opinion of the investigator, would affect the subject's ability to complete study assessments, or which would not be in the subject's best interest to participate in the study * Presence of orthostatic hypotension at screening: a decrease in systolic blood pressure (at least 20 mm Hg) or diastolic blood pressure (at least 10 mm Hg) within 3 minutes of the subject standing up, compared to pressures obtained while sitting * If female, is pregnant or lactating * If a sexually active female, is not surgically sterile or at least 2 years post-menopausal, or does not agree to utilize a highly effective hormonal method of contraception (an IUD, or vasectomized male partner is also acceptable), in combination with a barrier method, from screening through at least 4 weeks after the completion of study treatment. If a sexually active male, does not agree to utilize condoms from screening through at least 4 weeks after the completion of study treatment. * Treatment with an investigational drug or device within 30 days prior to screening * Treatment with an investigational biologic within 6 months or 5 half-lives, whichever is longer, prior to screening