To evaluate whether dexpramipexole prolongs the QTc interval when orally administered to healthy volunteers.

This is a Phase I, single-center, blinded (with respect to dexpramipexole administration), randomized, placebo- and active-controlled, 4-period crossover study in approximately 68 healthy volunteers. This thorough QT/QTc study will be conducted to formally evaluate the effect of dexpramipexole on QT prolongation.

Inclusion Criteria:

• Aged 18 to 60 years old inclusive on Day 1.
• Subjects who, in the opinion of the Investigator, are healthy as determined by pre study medical history, physical examination, and 12 lead ECG.
• Male subjects and female subjects of childbearing potential must practice effective contraception (per protocol specifications).
• Normal systemic blood pressure defined as a systolic blood pressure of 90 to 140 mmHg and a diastolic blood pressure of 50 to 90 mmHg.

Exclusion Criteria:

• History of cardiovascular disease (e.g., hypertension, arrhythmia, heart failure, Long QT Syndrome, or other conditions/diseases causing prolongation of the QT/QTc interval), in the opinion of the Investigator.
• A prolongation of QT/QTc interval (e.g., repeated demonstration of a QT/QTc interval >450 ms before study treatment administration.
• Clinically important abnormalities in resting ECG that may interfere with the interpretation of QTc interval changes at screening, check-in, or pre-dose on Day -1 of the first treatment period.
• Other medically significant illness.
• Clinically significant abnormal laboratory values.
• Pregnant women or women breastfeeding.