Viagra, or sildenafil, primarily works by inhibiting phosphodiesterase-5 (PDE5). This enzyme normally breaks down cyclic guanosine monophosphate (cGMP), a molecule crucial for smooth muscle relaxation. By blocking PDE5, Viagra increases cGMP levels.
This increased cGMP leads to vasodilation, particularly in the blood vessels of the penis. Improved blood flow is the key to Viagra’s effect on erectile function.
Nitric oxide (NO) plays a vital role in this process. NO stimulates the production of cGMP. Therefore, Viagra’s action synergizes with the NO pathway. Combining Viagra with NO-donating drugs, like nitroglycerin, can lead to dangerously low blood pressure because of the amplified vasodilation.
| Nitric Oxide (NO) | Stimulates cGMP production | Synergistic; increased vasodilation |
| CGMP | Causes smooth muscle relaxation | Increased levels enhance Viagra’s effect |
| Phosphodiesterase-5 (PDE5) | Breaks down cGMP | Inhibited by Viagra, prolonging cGMP’s effects |
Consequently, understanding this interaction is crucial for safe medication use. Consult your doctor before combining Viagra with other medications, especially those containing nitrates or NO donors. Always follow prescribed dosages.
