Intagra is a generic (analogue) of the well-known drug Viagra (sildenafil), which is used to treat erectile dysfunction (ED) in men. The active ingredient is sildenafil citrate, which belongs to the group of phosphodiesterase type 5 (PDE-5) inhibitors. Intagra is available in tablet form, usually in dosages of 25 mg, 50 mg and 100 mg.