Malegra 200 mg belongs to a class of drugs known as PDE5 inhibitors. Sildenafil Citrate works by inhibiting the action of the phosphodiesterase type 5 (PDE5) enzyme, which is responsible for reducing blood flow to the penis after an erection. By blocking PDE5, Sildenafil promotes the production of cyclic GMP, a molecule that relaxes the blood vessels in the penis and improves blood flow during sexual arousal.