Intravenous steroids are safe and effective in treating acute exacerbations of MS. Its use is directed at the early halting or diminishing of the destructive inflammatory process in the central nervous system, so that neurologic disability doesn't accumulate. For an acute relapse, a course of intravenous corticosteroids is typically given (500 mg to 1 gram of methylprednisolone (Solu-Medrol) over 30 to 60 mins for 3 days). This course can be extended up to 5 days (or to even 10 days) if the attack continues to progress or is slow in improving. Intravenous methylprednisolone is also the usual primary treatment for optic neuritis. The somewhat rapid effect of steroid treatment is based partly by reduction of white matter edema, and somewhat by an alteration of immunological factors. It is unusual in practice to give more than 2 or 3 courses of steroids for the treatment of relapses.
In a thorough QT interval study of doses of or mg fingolimod at steady-state, when a negative chronotropic effect of fingolimod was still present, fingolimod treatment resulted in a prolongation of QTc, with the upper boundary of the 90% confidence interval (CI) of msec. There is no consistent signal of increased incidence of QTc outliers, either absolute or change from baseline, associated with fingolimod treatment. In MS studies, there was no clinically relevant prolongation of the QT interval, but patients at risk for QT prolongation were not included in clinical studies.