Given the fact that PDE-5 drugs are responsible for cGMP breakdown, which in its turn is not only present in penis, but also lungs vessels, sildenafil, as an inhibitor of the enzyme, boosts up cGMP concentration in vascular smooth muscle cells of the lung, promoting their their relaxation. In clinical practice those suffering from pulmonary hypertension are sometimes appointed the medicine to primarily contribute to the expansion of the lungs and blood vessels, and to a lesser extent other blood vessels. In patients taking with sildenafil, mean pulmonary artery pressure is decreased significantly compared to placebo. With sildenafil citrate use the share of patients that have managed to shift to a healthier functional class described in WHO classification within a 12 weeks trial was significantly higher in placebo group. Thus, 28, 36 and 42% of patients respectively taking 20, 40 and 80mg sildenafil is no way near the 7% improvement achieved with placebo. Furthermore, treatment with sildenafil versus placebo resulted in improved quality of life, especially in terms of physical activity, and the trend to improved dyspnea index.
Sildenafil causes a small and transient decrease in blood pressure (BP), which in most cases is not accompanied by clinical symptoms. At single, up to 100mg doses of sildenafil taken orally by healthy patients, there was no significant effect revealed at ECG. In the clinical trial of the hemodynamic effects in those suffering from severe coronary atherosclerosis, sildenafil produced no significant cardiac output, and didn't impair blood flow in stenotic coronary arteries. Therefore, Viagra, based on sildenafil citrate, can treat pulmonary hypertension with chances for positive outcome quite high, is one of the few cost-effective pulmonary hypertension pills to get online with no prescription needed.
Although some patients showed mild and transient impaired ability of color perception (blue/green); over 2 hours after taking the medication these changes disappeared. It is believed that a violation of color vision caused by the inhibition of PDE-6, involved in the transmission of light in the eye retina. Sildenafil has no influence on the sharpness of vision, contrast perception, electroretinography data, intraocular pressure or the diameter of the pupil. In patients with confirmed primary age macular degeneration, the maximum dosage of medication of100 mg didn't cause significant changes in visual functions, such as visual acuity, estimated using the ability to distinguish colors of a traffic light.