phosphodiesterase type 5 inhibitors

Phosphodiesterase type 5 (PDE5) inhibitors are medications used primarily to treat erectile dysfunction and pulmonary hypertension. They work by blocking the PDE5 enzyme, which breaks down a molecule called cyclic GMP that helps relax blood vessels. By preventing this breakdown, PDE5 inhibitors promote increased blood flow to certain areas, such as the penis, facilitating an erection, or to the lungs, improving blood pressure. Common PDE5 inhibitors include sildenafil (Viagra), tadalafil (Cialis), and vardenafil (Levitra). They are effective when taken before sexual activity or as prescribed, but require sexual arousal to work.