| Approximately 140 million men worldwide are estimated to suffer from erectile dysfunction. Over half of all men with ED are considered to have some organic (medical) cause. The remainder are supposed to have psychological causes of impotence. Medical causes of sexual dysfunction are diabetes and nerve damage, vascular disorders or urological conditions.
Penile erection happens when the blood vessels carrying blood to the penis increase the delivery of blood and the blood flow from the penis declines. Under normal conditions, sexual arousal results in the production and release of nitric oxide in the penis. Afterwards, nitric oxide activates the enzyme, guanylate cyclase, which triggers the production of cyclic guanosine monophosphate (cGMP). It is the cGMP that is primarily responsible for the erection by controlling the amount of blood is delivered and carried away from the penis.
Viagra is prescribed for the treatment of ED of either organic or psychogenic condition. Viagra inhibits an enzyme called phosphodiesterase-5 (PDE5) that destroys the cGMP. Hence, sildenafil precludes the destruction of cGMP and allows cGMP to increase in quantity and persist longer. The longer cGMP persists, the more elongated the engorgement of the penis.
Viagra is rapidly absorbed. Maximal observed plasma concentrations are reached within 30 to 120 minutes of oral dosing in the fasted state. When sildenafil is taken with a high fat meal, the rate of absorption is reduced, with maximal concentration observed in an hour.
Sildenafil increases the effects of the blood pressure lowering drugs and nitrates that are prescribed chiefly for treating angina. Therefore, drug-to-drug interactions with heart medications and nitrates can be life-threatening.
Approximately 15% of patients taking sildenafil have side effects. The most common side effects are splitting headaches, indigestion, facial flushing and visual changes.
Speak with your physician before taking sildenafil. If you are allowed to use Viagra, stringently follow the recommended dose. |
