Plasma concentration–time profiles for (A) midazolam, (B) S‐warfarin, (C) omeprazole and (D) caffeine following administration of a probe drug cocktail alone or with daclizumab high‐yield process (DAC HYP) in patients with multiple sclerosis. Mean and standard deviation for midazolam (n = 19), S‐warfarin (n = 19), omeprazole (n = 18) and caffeine (n = 12). Treatment: () Cocktail alone, () Cocktail + DAC HYP