Safety and Tolerability of ISX (Isoxsuprine HCL) in MS Relapses

Inclusion Criteria

• 1. Subjects must be adequately informed and understand the nature and risks of the study and must be able to provide a signature and date on the ICF; 2. Male or female subjects between 18 and 50 years of age, inclusive; 3. Confirmed diagnosis of Multiple Sclerosis or Clinically Isolated Syndrome (CIS) suggestive of MS, according to the 2010 Revised McDonald criteria.
• On a stable regimen of medications taken specifically to treat MS for at least 30 days prior to screening, and willing to continue the same doses and regimens for the duration of study participation; 5. New neurological disability consistent with MS relapse no longer than 7 days prior to screening; 6. Screen visit and randomization must occur within 48 hours of subject initiating steroid treatment.
• Maximum EDSS score during screening of 6.5; 8. Sufficient ambulatory ability (ambulatory aids acceptable if used consistently) to complete two trials of the Timed 25 Foot Walk (T25FW) at the screening visit with the two trials completed within 5 minutes of each other in accordance with the specific instructions provided by the National MS Society Functional Composite Manual.
• Subject must be willing to take a high dose steroid (600mg oral prednisone two times a day (bid).
• Subjects must have a mean systolic blood pressure ≤ 160 and greater than 100 mm Hg and a mean diastolic blood pressure of ≤ 100 and greater than 50 mm Hg determined by the average of 3 seated readings taken at least 5 minutes apart at the Screening Visit.
• Subjects must be able to communicate effectively with study personnel. For this reason only English speaking subjects will be eligible for the study.
• Subjects must be able and willing to follow all protocol requirements and study restrictions.
• Subjects must be able and willing to return for all study visits.

Exclusion Criteria

• 1. Subject is from a vulnerable population, as defined by the US CFR Title 45, Part 46, Section 46.111(b) and other local and national regulations, including but not limited to, employees (temporary, part-time, full time, etc) or a family member of the research staff conducting the study, or of the sponsor, or of the IRB.
• Subject has only sensory, bowel/bladder, and/or cognitive symptoms of MS associated with the most recent relapse.
• Subject has cognitive or behavioral impairment that in the opinion of the investigator would impair the ability of the subject to comply with study procedures.
• Subject has any known contraindication(s) to the use of corticosteroids or isoxsuprine hydrochloride (ISX), including, but not limited to:
• any current uncontrolled hypertension, primary adrenocortical insufficiency
• Any current psychoses, infectious disease, or Cushing's syndrome.
• Any current congestive heart failure (defined as New York Heart Association (Functional Class III to IV).
• Peptic ulcer (within 24 weeks prior to the Screening Visit).
• Recent major surgery (within 24 weeks prior to the Screening Visit).
• Use of tizanidine any time in the past 30 days. 5. Subject has a clinically significant infection requiring intravenous administration of antibiotics and hospitalization prior to the Screening Visit.
• Subject has poorly controlled type 1 or type 2 diabetes mellitus (prior diagnosis of gestational diabetes mellitus is not exclusionary 7. Received systemic steroids for a problem unrelated to the MS relapse within 30 days prior to screening.
• History of other neurological disease that, 'in the opinion of the Investigator, would affect motor function or cognition; 9. For patients with a history of Major Depressive Disorder, at risk for worsening depression due to steroids or the presence of active depressive symptoms sufficient, in the opinion of the investigator, to 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; 10. Presence of cognitive impairment sufficien