Medical Encyclopedia

Viagra Professional is based on sildenafil citrate, a substance famous for its stimulating effect on male erectile function. Sildenafil's improves erection by blocking phosphodiestraze 5 (PDE5), an enzyme, which controls blood flow to penile chambers. At the same time, sildenafil stimulates the production of cyclic guanosine monophosphate (cGMP), which acts opposite to PDE5.

Viagra Professional does not treat the disease, which causes impotence. Usually, erection problems come as symptoms of cardiac disorders, diabetes, low blood pressure and stress. Cyclic guanosine monophosphate's production is stimulated by nitric oxide, which is synthesized during sexual excitement. Therefore, Viagra is only effective during sexual arousal, and hence it should be taken at least 30 minutes before sex. Viagra's effect lasts about 4 hours. Viagra Professional has a longer action (up to 8 hours).

Although Viagra Professional is based on an advanced formula and therefore is less likely to generate adverse events, it still contains sildenafil citrate, which is not intended for everyone. There is a lot of discussion among doctors on whether or not Viagra affects the work of the heart positively. There have been reports about deaths among cardiac patients, who have been using sildenafil, but studies have shown that these deaths were due to underlying diseases (heart insufficiency, arrhythmia, miocardiac infarction, etc.).

Recent studies have discovered a few properties of Sildenafil, which may pay the way for is not only as an ED medicine, but also as a treatment for heart problems. According to David Kass, a professor at The Johns Hopkins University School of Medicine, sildenafil has shown a remarkable ability to relieve stress on the heart, brought on by emotional upheavals. A group of men and women, who had no history of heart disorders, participated in an experiment. Part of the group was using Sildenafil, and the other part was not. Each participant received an injection of dobutamine, a substitute for adrenaline, which increases heart rate. In the sildenafil group, heart rates were slower, and there were no signs of any adverse effects on the heart. Studies on mice revealed Sildenafil's ability to reverse the heart muscle impaired by a heart attack or hypertrophy.

There have been other attempts to study Viagra's effect on cardiac function, and one of them revealed an ability of sildenafil to prolong cardiac repolarization, an effect similar to that of some antyarrythmic drugs. This may impact the work of the heart and cause a sudden death. Although it takes a very large dose for sildenafil to exert visible influence on the heart, there is an increased risk of consequences for people suffering hepatic impairment due to slow drug elimination and hence high plasma concentrations of sildenafil.