Men with erectile dysfunction (ED) can be treated with Penegra, a brand of sildenafil citrate, the same active ingredient in Viagra.  Penegra, which is produced by Zydus Cadila, comes in tablet form in 50 mg and 100 mg dosages. How It Operates By relaxing blood vessels, Penegra acts as a phosphodiesterase type 5 (PDE5) inhibitor, increasing blood flow to the penis during sexual...