Vardenafil usually works for 4 to 5 hours. You can take sildenafil with or without food. Generic versions of sildenafil, vardenafil and tadalafil are available. This medicine also works best when you take it an hour before sex on an empty stomach. These medicines all work well for ED. How oral medicines differ Each oral medicine for ED has a slightly different chemical makeup.Sildenafil Prices, Coupons and Patient Assistance Programs. Sildenafil is a member of the agents for pulmonary hypertension drug class and is commonly used for Erectile Dysfunction, Pulmonary Arterial Hypertension, and Sexual Dysfunction – SSRI Induced.. Brand names for sildenafil include Viagra, Revatio, and Liqrev. The cost for sildenafil . Cost: Branded Viagra is priced at $90 per dose regardless of the milligram dosage and you will be able to work with your prescriber to find which dosage is right for you. Sildenafil is also. Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 inhibitors. They enhance the effects of a chemical the body makes that relaxes muscles in the penis, called nitric oxide. This boosts blood flow and helps you get an erection from sexual g: dollar general.