The penis is one of the areas where this enzyme works. Stendra avanafil : This is an as-needed medication taken 30 minutes before sex and can last up to six hours. The decision, Teva Canada Ltd. Seven of these companies are based in India. When hypertension occurs in the lungs, the heart must work harder to pump enough blood through the lungs. Severe liver disease. You’ll soon start receiving the latest Mayo Clinic health information you requested in your inbox. · To use the oral liquid: Shake the bottle well for at least 10 seconds before each use. Remove the cap by pushing it down and twisting it counter-clockwise. Push . Avanafil (Stendra). Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 inhibitors. They enhance the effects of a chemical the body .  · Sildenafil under the name Viagra is used to treat erectile dysfunction (impotence) in men. Another brand of sildenafil is Revatio, which is used to treat .