Which PDE5 inhibitors are there?

PDE5 inhibitors are a class of medications commonly used to treat erectile dysfunction (ED) and pulmonary arterial hypertension (PAH). They work by blocking the phosphodiesterase type 5 (PDE5) enzyme, which is responsible for breaking down a molecule called cyclic GMP. Cyclic GMP helps relax the smooth muscles and dilate blood vessels, particularly in the penis, allowing for increased blood flow and enabling an erection during sexual arousal.