About the brand of the drug.
Fildena 150 is a brand produced by Fortune Healthcare India for the purpose of treating male impotence, also known as erectile dysfunction (inability to maintain or achieve an adequate erection during intercourse). Fildena contains the popular Sildenafil Citrate salt, first launched as Pfizer's Viagra. It comes in a pack of 10 tablets, purple in color and triangular in shape. It is readily available in online pharmacies, but you need to present a prescription to buy it.

on drugs
Fildena is a registered trademark of Fortune Healthcare India used for the purpose of branding Sildenafil citrate tablets. Fildena is available in various strengths i.e. 25mg, 50mg, 100mg and 150mg with a minimum market price of $ 0.69 in the U.S. Sildenafil Citrate is characterized as a PDE-5 drug, which are used to treat the problem of male impotence and some of them are also used to treat pulmonary hypertension. Sildenafil citrate marketed as Lovegra is used to increase libido in women.

On the drug salt.
As mentioned above, the active pharmaceutical ingredient in Fildena 120mg is Sildenafil Citrate, the popular drug on the market like Pfizer's Viagra. Sildenafil was first discovered by Pfizer in 1989 for the treatment of heart-related chest pain. It was accepted for medical use in the United States and Europe in  its patent expired and generic versions started coming out. It works by deactivating an enzyme in our body called PDE5 or phosphodiesterase-5 which causes increased blood flow to the penis and is capable of causing a prolonged and sustained erection in men.

drug work
As previously mentioned, Sildenafil Citrate works by increasing blood flow to the penis causing a long and prolonged erection. To understand how this drug affects, let's first understand the anatomy of male erection. A male erection is achieved when a chemical called NO  is produced in the male p*nis which internally activates an enzyme called "guanylate cyclase". This guanylate cyclase converts a natural chemical in the body called GTP into C-GMP and this C-GMP is responsible for erections. Sildenafil deactivates the PDE-5 enzyme which is responsible for breaking down GMPs. In simpler language, sildenafil breaks down the enzyme which is responsible for lowering the erectile effect of another enzyme Sildenafil citrate has the highest oral absorption compared to other drugs of the same class, up to  absorbed orally. Sildenafil takes about 1 hour to reach its 

Fildena 100

Fildena Super Active