These include itraconazole Sporanox, Tolsura , ketoconazole Extina, Ketozole, others and ritonavir Norvir. How oral medicines differ Each oral medicine for ED has a slightly different chemical makeup. When oral medications might not be safe Check with your health care team before you take any medicine for erectile dysfunction. To provide you with the most relevant and helpful information, and understand which information is beneficial, we may combine your email and site usage information with other information we have about you. Oral medicines for ED usually work well and cause few side effects. · Drug information provided by: Merative, Micromedex ® US Brand Name Revatio Viagra Descriptions Sildenafil is used to treat men who have erectile dysfunction (also called sexual impotence). Sildenafil belongs to a group of medicines called phosphodiesterase 5 (PDE5) inhibitors. 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 activity. How oral medicines differ. generic Viagra (sildenafil) generic Cialis (tadalafil) brand-name Viagra; brand-name.