Kidney disease that needs to be treated with dialysis. These medicines all work well for ED. This medication is taken with or without food an hour before sex. Soon, these are expected to flood the market, as manufacturers jostle for a slice of the pie. Please expect up to 4 to 6 weeks for reimbursement. This patent was published in and expired in Viagra basics. The active drug in Viagra is sildenafil. It belongs to a group of drugs called phosphodiesterase-5 inhibitors. Viagra comes as tablets you take by mouth. Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 inhibitors. They enhance the effects of a chemical the body makes that relaxes . CHOOSE BRAND-NAME VIAGRA. The original little blue pill prescribed by doctors for over 20 years. Clinically proven to treat men with erectile dysfunction (ED) Ongoing .