Suhagra 100 mg contains Sildenafil Citrate, which is used to treat erectile dysfunction (ED) in men. Its action in the body involves a series of chemical and vascular processes. During sexual stimulation, the penis naturally releases nitric oxide (NO) in the erectile tissue. Nitric oxide activates an enzyme called guanylate cyclase, which increases levels of cyclic guanosine monophosphate (cGMP). This molecule relaxes the smooth muscles in the blood vessels of the penis, allowing them to dilate and fill with blood, producing an erection.