Sildenafil Citrate Chewable Tablet contains Sildenafil. This active drug works to inhibit an enzyme, which stops the degradation of a vasodilator called cGMP. The increase of cGMP, in turn, helps to relax the muscles in the body. Next, nitric oxide works to increase the blood flow to the male organ. This reaction leads to an erection when a man is sexually stimulated. This drug works efficiently within 30 minutes.