Oct 15, 2022 09:00:00

What is the reason why Viagra works not only for erectile dysfunction but also for lung diseases?

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Viagra (sildenafil) '' is known as a remedy for erectile dysfunction, and in Japan from April 2022, it will be covered by public medical insurance only if it is diagnosed as `` male infertility due to erectile dysfunction ''. Such sildenafil is used not only for erectile dysfunction but also for the treatment of pulmonary diseases with a poor prognosis, explains Tyler Pitre et al.

Medications for the treatment of pulmonary arterial hypertension: a systematic review and network meta-analysis | European Respiratory Society
http://doi.org/10.1183/16000617.0036-2022

Why Viagra may be useful in treating lung diseases
https://theconversation.com/why-viagra-may-be-useful-in-treating-lung-diseases-188041

Sildenafil is a drug originally developed as a therapeutic drug for angina pectoris , and it inhibits the enzyme phosphodiesterase to help relax smooth muscle and vasodilate in blood vessels. This brings more blood to the organ and promotes and maintains an erection of the penis.

This vasodilatory effect also benefits organs other than the penis, and is effective in treating refractory pulmonary diseases such as pulmonary arterial hypertension (PAH) and idiopathic pulmonary fibrosis (IPF) that cause chronic shortness of breath and cough. It is said that there is Sildenafil is approved for the treatment of PAH in Canada and is prescribed under the brand name Revatio . Pitre says there is little difference between Viagra and Revatio, except for dosage.

PAH is a disease in which small blood vessels in the lungs become narrowed, resulting in abnormally increased pressure in the pulmonary arteries that carry blood from the heart to the lungs. Pitre and colleagues reviewed the results of multiple studies with a total of more than 10,000 patients and analyzed the effects of Revatio and other similar drugs on PAH.

Results showed a 12.7% reduction in clinical exacerbations, such as PAH progression and hospitalization, in drug-treated patients compared to controls. The research team also reported that the 6-minute walking distance, which was measured as an index of exercise capacity, was 50 m longer when the drug was taken.

On the other hand, IPF is a disease in which lung cells are repeatedly damaged over a long period of time, resulting in thickening of the

interstitium through which oxygen and carbon dioxide pass, resulting in fibrosis. If the lungs become fibrous, they will not expand well during breathing, and gas exchange will be insufficient, making it difficult to breathe.

Although there are not many studies examining the association between IPF and sildenafil, a study that analyzed four randomized controlled trials reached near statistical significance. In addition, a study on a drug called treprostinil , which has a vasodilator effect similar to that of sildenafil, showed promising results in the treatment of pulmonary diseases, including IPF, suggesting that sildenafil may also be effective. It has been.

The advantage of using sildenafil for the treatment of PAH and IPF is that ``developing new drugs is expensive, but repurposing existing drugs can reduce development costs.'' In addition to this, Mr. Pitre points out that ``existing drugs have abundant data on safety,'' because sildenafil is widely used around the world as ``Viagra'' and there is abundant data on side effects. .

For example, sildenafil is known to cause low blood pressure and should be avoided by people who are susceptible to low blood pressure or who are taking high blood pressure medications. It has also been found to have side effects such as facial redness, headaches, and changes in vision.

``Sildenafil may not be the magic pill for all lung ailments, but it clearly has promising uses beyond erectile dysfunction,'' Pitre said.