What should I do if I forget a dose? BPH is caused by an enlarged prostate. Tadalafil is in a class of medications called phosphodiesterase PDE inhibitors. These medicines prevent an enzyme called phosphodiesterase type-5 from working too quickly. Take tadalafil at around the same time every day.Generic name: tadalafil [ ta-DAL-a-fil ] Brand names: Adcirca, Cialis. Drug classes: Agents for pulmonary hypertension, Impotence agents. Medically reviewed by . What is Cialis? Cialis relaxes muscles of the blood vessels and increases blood flow to particular areas of the body. Cialis is used to treat erectile dysfunction .  · What is Cialis? Cialis is a brand-name prescription medication. It’s FDA-approved to treat the following in males:* erectile dysfunction (ED), a condition in which .