Patients with pain caused by narrowed arteries in their legs have 37 percent more pain-free walking if they take naftidrofuryl (200 mg three times a day) than those taking placebos, a Cochrane Review has found. In addition, 55 percent of patients taking naftidrofuryl improved, while only 30 percent of people on placebo treatments improved. Naftidrofuryl is used to treat circulatory problems.