Sildenafil citrate, a drug used to treat erectile dysfunction (ED), is marketed under the name Filagra. Men of all ages are susceptible to ED, a prevalent disorder. The inability to achieve or sustain an erection that is sufficiently firm for sexual activity is its defining feature.Filagra is an inhibitor of phosphodiesterase type 5 (PDE5). An enzyme called PDE5 degrades cGMP, a substance that aids in erection by relaxing the penile muscles. Filagra helps to raise cGMP levels in the penis by blocking PDE5, which may enhance erectile function. About half an hour before engaging in sexual activity, 50 milligrams (mg) of filagra is taken as a single dose.