Sildenafil is the name of the chemical ingredient contained in Pfizer Viagra as well the generic Viagra medications available in the market and online pharmacies. Sildenafil is used to treat erectile dysfunction in men and also used as a treatment for pulmonary arterial hypertension. Sildenafil was the first oral treatment available for erectile dysfunction. Erectile dysfunction is the condition where a person cannot achieve or maintain an erection for the course of sexual intercourse. It severity ranges from being completely unable to achieve an erection to achieving an erection initially but losing it or being unable to maintain it for the span of sexual intercourse. As frustrating as it is to suffer from erectile dysfunction, the treatment has become a lot easier nowadays thanks to the medical advancements.
Although Sildenafil was originally developed by a group of chemists working for Pfizer based in England for the treatment of high blood pressure and angina pectoris (a symptom of ischaemic heart disease), clinical trials suggested that it was ineffective in the treatment of angina but it was quite effective in inducing penile erection. Hence, Sildenafil was marketed for the treatment of erectile dysfunction rather than angina. Pfizer patented Sildenafil in 1996; however the FDA approved the use and sale in 1998. Soon after its launch under the brand name Viagra, it became a huge success and generated US $1.934 revenue for Pfizer in a single year. Even after the introduction of Cialis and Levitra as alternatives to Viagra, its sales accounted for 92% of the global market for the treatment of erectile dysfunction.
How does Sildenafil work?
Cyclic guanosine monophosphate (cGMP) is degraded by cGMP specific phosphodiesterase type 5 (PDE5). This action results in the loss of erection. Sildenafil works by inhibiting the PDE5 and thereby helping in erection. Sildenafil in itself is not responsible for an erection. cGMP is responsible for the erection. An increased level of cGMP relaxes the smooth muscles inside the penis thereby causing an erection. Sildenafil is similar in its molecular structure to cGMP. Hence, it binds easily with PDE5 instead of cGMP. This results in an increased amount of cGMP spared from being bound with PDE5.
This means that for an erection cGMP must be produced in the body in the first place. When a person receives enough sexual stimulation Nitrous oxide (NO) is produced in the corpus cavernosum of the penis. Nitrous oxide then binds to guanylate cyclase receptors which results in increased levels of cGMP. An increase or presence of Sildenafil cannot produce an erection.
Sildenafil remains effective for almost 8 hours. The average time required for Sildenafil to produce the results is 27 minutes when taken by mouth and the average time to produce the results is 15 minutes when taken under the tongue. High fat meal prevents the absorption of Sildenafil. It increases the time taken to reach the maximum plasma concentration by one hour and decreases the maximum concentration by nearly one third. Sildenafil 100 mg is the regular dosage prescribed for erectile dysfunction. It is not prescribed as a once daily medication. It must be only taken when required. It should also be not taken twice in 24 hours.
One should not take Sildenafil if:
• They are on a nitric medication
• They are advised not to engage in sexual activities owing to their cardiovascular health
• They suffer from hepatic impairment
• They suffer from kidney diseases
• They suffer from low blood pressure
• They had a recent heart attack
• They had a recent stroke
• They have a retinal disorder
Not everyone experiences a side effect. If you suffer from any side effect, you can always switch to a lower dosage strength.
The most common side effects of Sildenafil are:
• Nasal congestion
• Impaired vision
• Back pain
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