|The mechanism of action for medications like sildenafil and tadalafil involves inhibiting an enzyme called phosphodiesterase type 5 (PDE5). Here's a general overview of how these medications work: Sexual arousal leads to the release of nitric oxide (NO) in the erectile tissue of the penis. Nitric oxide stimulates the production of cyclic guanosine monophosphate (cGMP). Cyclic GMP is a signaling molecule that relaxes the smooth muscles in the walls of blood vessels leading to the penis. This p force relaxation allows the blood vessels to dilate, increasing blood flow to the erectile tissue. PDE5 Inhibition: Phosphodiesterase type 5 (PDE5) is an enzyme that breaks down cGMP. When cGMP is broken down, the blood vessels constrict and blood flow decreases, making it difficult to maintain an erection. Medications like sildenafil and tadalafil are known as PDE5 inhibitors. They work by blocking the action of PDE5, preventing it from breaking down cGMP. This allows cGMP to accumulate, leading to sustained relaxation of the blood vessels and increased blood flow to the penis. As a result, men with ED can achieve and maintain an erection when sexually aroused.