A phosphodiesterase (PDE-5) inhibitor is tadfil. By relaxing the muscles in the penile blood vessels, it increases blood flow to the penis in cases of erectile dysfunction. It reduces pulmonary hypertension by facilitating easier blood flow by relaxing the lungs' blood vessels.

Tadalafil enhances blood flow to specific body parts by relaxing the blood vessel muscles.

Cialis, a brand name for tadalafil, is used to treat impotence, or erectile dysfunction, and the symptoms of benign prostatic hypertrophy, or an enlarged prostate. Adcirca is a different brand of tadalafil that is used to treat pulmonary arterial hypertension and increase both men's and women's ability to exercise.