Subjects in the study will receive either pirfenidone (2403 mg every day) or placebo capsules (a safe, inactive substance that will look the same as the pirfenidone capsules). Both the placebo and pirfenidone will be supplied in opaque, hard, white gelatin capsules and will be taken as 3 capsules by mouth, 3 times a day (a total of 9 capsules per day) and should be taken with food.