CAS 171599-83-0 API Active Pharmaceutical Ingredient Sildenafil Citrate Powder

Description

Sildenafil citrate is the raw material of , treats erectile dys function and works by relaxing muscles and increases blood flow to particular areas of the body (in this case, the penis, specifically). Its effects last up to four hours. The most common side effects of are headache, facial flushing, and upset stomach. Rarely, blurred vision, or sensitivity to light may briefly occur.

As well as treating impotence, Sildenafil Citrate can also be effective in treating Pulmonary Arterial Hypertension (PAH). Similarly to how it acts to relax muscles of the penis, it relaxes arterial walls; therefore, reducing resistance and pressure in the arteries.

Sildenafil Citrate is solely active in relaxing muscles and increasing blood flow to the heart, lungs and penis due to PDE-5, yet vasodilation is not increased in other parts of the body.

Applications

1. Sexual dysfunction

The primary indication of sildenafil is treatment of erectile dysfunction (inability to sustain a satisfactory erection to complete intercourse). Its use is now standard treatment for erectile dysfunction including for those with diabetes mellitus.

2. Pulmonary hypertension
As well as erectile dysfunction, sildenafil citrate is also effective in the rare disease pulmonary arterial hypertension. It relaxes the arterial wall, leading to decreased pulmonary arterial resistance and pressure. This, in turn, reduces the workload of the right ventricle of the heart and improves symptoms of right-sided heart failure. Because PDE5 is primarily distributed within the arterial wall smooth muscle of the lungs and penis, sildenafil acts selectively in both these areas without inducing vasodilation in other areas of the body. Pfizer submitted an additional registration for sildenafil to the United States Food and Drug Administration (FDA), and sildenafil was approved for this indication in June 2005. The preparation is named Revatio, to avoid confusion with , and the 20-mg tablets are white and round. Sildenafil joins bosentan and prostacyclin-based therapies for this condition.

Mechanism Of Action

The physiologic mechanism of erection of the penis involves release of nitric oxide (NO) in the corpus cavernosum during sexual stimulation. NO then activates the enzyme guanylate cyclase, which results in increased levels of cyclic guanosine monophosphate (cGMP), producing smooth muscle relaxation in the corpus cavernosum and allowing inflow of blood.

Sildenafil enhances the effect of NO by inhibiting phosphodiesterase type 5 (PDE5), which is responsible for degradation of cGMP in the corpus cavernosum. Sildenafil has no direct relaxant effect on isolated human corpus cavernosum. When sexual stimulation causes local release of NO, inhibition of PDE5 by sildenafil causes increased levels of cGMP in the corpus cavernosum, resulting in smooth muscle relaxation and inflow of blood to the corpus cavernosum. Sildenafil at recommended doses has no effect in the absence of sexual stimulation.