Zenegra 100 mg is considered a PDE5 inhibitor because its active ingredient, Sildenafil Citrate, works by inhibiting an enzyme called PDE5 (phosphodiesterase type 5). Here's how it works in more detail: What Is PDE5 and How Does It Relate to Erectile Dysfunction? PDE5 (phosphodiesterase type 5) is an enzyme found in various tissues throughout the body, including the penis, lungs, and other organs. In the penis, PDE5 breaks down cGMP (cyclic guanosine monophosphate), a substance that plays a key role in relaxing smooth muscle and allowing increased blood flow to the area. Erectile dysfunction (ED) occurs when there is insufficient blood flow to the penis, typically due to the narrowing of blood vessels or insufficient relaxation of smooth muscle in the penile tissue. How Does Sildenafil (Zenegra) Work as a PDE5 Inhibitor? When you take Zenegra 100 mg , Sildenafil works by inhibiting PDE5, which prevents the breakdown of cGMP in the penis. Increased levels of cGMP allow the smooth muscle in the blood vessels of the penis to relax, which results in dilated blood vessels and increased blood flow. This enhanced blood flow helps achieve and sustain an erection when sexually stimulated. Summary of the Mechanism: Sexual arousal leads to the release of nitric oxide in the penis, which activates guanylate cyclase to increase the production of cGMP. cGMP causes the smooth muscle of the blood vessels in the penis to relax, allowing blood to flow in and produce an erection. PDE5 usually breaks down cGMP, limiting the erection process. Sildenafil (Zenegra 100 mg) inhibits PDE5, so cGMP remains active for longer, prolonging the erection. Why is This Important for ED Treatment? By inhibiting PDE5, Zenegra 100 mg allows the body’s natural erectile response to occur more effectively. It does not directly cause an erection but makes it easier for an erection to happen when sexual stimulation occurs. Why Zenegra 100 mg is Specifically a PDE5 Inhibitor: PDE5 inhibitors are a class of drugs used to treat erectile dysfunction by enhancing the natural erectile response.