Suhagra helps to increase the blood flow in the penile region. Sildenafil Citrate is present as an active medicament in Suhagra. This drug stays active for 3 to 4 hour after administration. Suhagra falls under the class of drug known as Phosphodiesterase type-5 inhibitor. Phosphodiesterase is an enzyme that decreases the formation of blood. This medication works by restricting the action of Phosphodiesterase enzyme.