Sildenafil citrate is the active component in the drug brand Fildena 100 mg. PDE-5 inhibitor sildenafil citrate treats erectile dysfunction (ED) in male patients. Fildena 100 empowers men to achieve and sustain erections that can reignite passion and intimacy. sildenafil citrate as its active ingredient, which belongs to a class of drugs known as phosphodiesterase type 5 (PDE-5) inhibitors. Sildenafil citrate works by inhibiting the action of the enzyme called PDE-5, which is responsible for the degradation of a compound called cyclic guanosine monophosphate (cGMP) in the penis. A sildenafil product with a high dosage, Fildena Double 200 is the active component. Men with severe or persistent ED are frequently prescribed one of the highest sildenafil doses available.