PST measures mental processing speed. The PST will be assessed using multiple sclerosis performance test (MSPT). The participants will be shown some symbols and corresponding numbers. The participants will be then asked to input the numbers corresponding to the given symbols in empty rows. Higher number of correct responses indicates better cognition

Neuro-QOL uses a T score which has a mean of 50 and SD of 10, based on the norming sample used. All Neuro-QOL banks and scales are scored such that a high score reflects more of what is being measured.

The PDDS has nine ordinal levels ranging between 0 (normal) and 8 (bedridden). Higher scores indicate greater disability.

The Work Productivity and Activity Impairment (WPAI) questionnaire is a validated instrument to measure impairments in work and activities. The WPAI yields four types of scores: 1. Absenteeism (work time missed) 2. Presenteesism (impairment at work / reduced on-the-job effectiveness) 3. Work productivity loss (overall work impairment / absenteeism plus presenteeism) 4. Activity Impairment. Higher numbers indicate greater impairment and less productivity.

An AE is any untoward medical occurrence in a participant administered a pharmaceutical product and that does not necessarily have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign (including an abnormal assessment such as an abnormal laboratory value), symptom, or disease temporally associated with the use of a medicinal (investigational) product, whether or not related to the medicinal (investigational) product.

An AE is any untoward medical occurrence in a participant administered a pharmaceutical product and that does not necessarily have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign (including an abnormal assessment such as an abnormal laboratory value), symptom, or disease temporally associated with the use of a medicinal (investigational) product, whether or not related to the medicinal (investigational) product.

An SAE is any untoward medical occurrence that at any dose results in death, in the view of the investigator, places the participant at immediate risk of death, requires inpatient hospitalization or prolongation of existing hospitalization, results in persistent or significant disability/incapacity, results in a congenital anomaly/birth defect or is a medically important event.

The actions taken will include temporary dose reduction, temporary dose interruption, initiation of concomitant GI medication, taking DRF dose with food, permanent discontinuation, or other action.