Sildenafil Generic sildenafil citrate Sildenafil Citrate basically is a phosphodiesterase (PDE-5) inhibitor which is an active ingredient of Cenforce Professional 100 mg tablet. It basically works in erectile dysfunction by increasing blood flow to the penis by relaxing the corpus cavernosum muscles in penile blood vessels in men. It also relaxes the blood vessels of the lungs to allow blood to flow more easily thereby helping in pulmonary hypertension.