Vigora 100 mg is a medication primarily used to treat erectile dysfunction in men. Its active ingredient is sildenafil citrate, which belongs to a class of drugs called phosphodiesterase type 5 (PDE5) inhibitors. The relationship between Vigora 100 mg and cyclic guanosine monophosphate (cGMP) is central to its mechanism of action. During sexual arousal, nitric oxide (NO) is released in the erectile tissue of the penis, which activates an enzyme called guanylate cyclase. Guanylate cyclase then catalyzes the conversion of guanosine triphosphate (GTP) to cGMP. cGMP acts as a signaling molecule, leading to relaxation of the smooth muscles in the penile arteries and corpus cavernosum, which results in increased blood flow to the penis and consequently, an erection. However, the enzyme PDE5 normally breaks down cGMP, leading to a decrease in its concentration and relaxation of the smooth muscles. This process limits the duration and strength of erections. Vigora 100 mg works by inhibiting the action of PDE5, thereby preventing the degradation of cGMP. As a result, cGMP levels remain elevated, allowing for prolonged and enhanced penile blood flow, which facilitates and maintains an erection during sexual stimulation. So, Vigora 100 mg indirectly enhances the effects of cGMP by preventing its breakdown, which leads to improved erectile function.