Sildenafil, the active ingredient in Fildena tablets, is a phosphodiesterase type 5 (PDE5) inhibitor primarily used to treat erectile dysfunction (ED). Sildenafil enhances blood flow to the penis by inhibiting PDE5, allowing for increased levels of cyclic guanosine monophosphate (cGMP). This results in smooth muscle relaxation and improved erectile function. Fildena and Sildalist 120 mg is prescribed for men experiencing difficulty achieving or maintaining an erection sufficient for sexual activity. It is effective when there is sexual stimulation. Sildenafil's effects typically last for about four to six hours after ingestion, providing a window of opportunity for sexual activity. Sildenafil is also used in higher doses to treat pulmonary arterial hypertension, a condition characterized by high blood pressure in the arteries of the lungs.