Sildenafil citrate is used to treating erectile dysfunction and pulmonary arterial hypertension (PAH). It works by inhibiting the enzyme, (cGMP) cyclic guanosine monophosphate-specific phosphodiesterase type 5 (PDE5). This enzyme works by promoting degradation of cGMP that regulates blood flow in the penis. The erection process is accompanied with sexual stimulation that releases nitric oxide into the penis. It reacts inside penis and form an enzyme cyclic guanosine monophosphate (cGMP). It loosens and relaxes the arterial wall of the penis and thus, erection is created. Once the artery of the penis becomes loose, it helps in easy engorgement of blood. The arteries are swollen, an erection is created.
Another enzyme called phosphodiesterase-5 is also present in the penis that helps in achieving erection. This enzyme degrades and reduces cyclic guanosine monophosphate within penis. This degradation is essential; else there will be constant erection.
Sildenafil citrate should be stored at room temperature between 15-30 degree centigrade. The medicine should be protected from light and moisture. This medicine should be kept at such a place where pet and child should not reach. The patient should check the expiry date of the medicine before using it.
Chemically, sildenafil citrate is designated as 1-[[3-(6,7-dihydro-1-methyl-7-oxo-3-propyl-1H pyrazolo[4,3-d]pyrimidin-5-yl)-4-ethoxyphenyl]sulfonyl]-4-methylpiperazine citrate. This appears as white to off-white crystalline powder and has a molecular weight of 666.7.
The medicine contains various inactive ingredients such as microcrystalline cellulose, anhydrous dibasic calcium phosphate, croscarmellose sodium, magnesium stearate, hypromellose, titanium dioxide, lactose, triacetin, and FD & C Blue #2 aluminium lake.
Sildenafil citrate is available under the brand name of Viagra, Revatio, etc. is a very powerful drug. This medicine was developed and marketed by a United States based pharmaceutical company, Pfizer.