Why Viagra May Help Treat Lung Disease – Brighter World

0

The dilation of blood vessels caused by sildenafil (Viagra) may be beneficial in lung diseases such as pulmonary arterial hypertension or idiopathic pulmonary fibrosis. (Shutterstock)

BY Tyler Pitre and Dena Zeraatkar, McMaster University; and Jasmine Mah, Dalhousie University

You may be surprised to learn that the drug sildenafil – better known by its brand name Viagra – has medical purposes other than treating male erectile dysfunction. It can also be used to treat lung diseases which often have poor prognoses.

Sildenafil works by inhibiting an enzyme called phosphodiesterase. Through a complex pathway involving other molecules, Sildenafil ultimately helps smooth muscles to relax and blood vessels to dilate. This latter effect is known as vasodilation. Vasodilation causes increased blood flow to organs, whether that organ is the penis or the lungs.

Lung diseases

The vasodilation caused by sildenafil may be beneficial in lung diseases such as pulmonary arterial hypertension (PAH) or idiopathic pulmonary fibrosis (IPF). People living with PAH and IPF suffer from progressive shortness of breath and chronic cough. In addition to the lungs, PAHs and IPF can affect many other organ systems.

PAH is a disease causing breathing difficulties and cardiac strains due to high pressure in the pulmonary arteries, which were designed for much lower pressures. Fortunately, it is a rare condition, affecting one or two in every 1,000,000 people each year.

IPF is a more common lung disease with between two and 29 in every 100,000 people developing the disease each year. It occurs due to repeated and chronic thickening, stiffening and scarring (fibrosis) of the lungs.

Both diseases often don’t have a clear etiology, which means doctors and researchers don’t fully understand why these diseases start and progress. Both of these diseases are incurable and often get worse over time despite our best treatment options. There are currently few effective treatments, and there is always interest in finding more.

Evidence of Sildenafil in PAH

There are currently few effective treatments for pulmonary arterial hypertension or idiopathic pulmonary fibrosis. (Shutterstock)

The use of sildenafil in PAH is already well established, effective and approved in Canada. There are several high-quality randomized controlled trials that have demonstrated its effectiveness in improving exercise capacity and symptom burden. Sildenafil is usually marketed as Revatio in PAH (instead of Viagra for erectile dysfunction), although there is little difference between Viagra and Revatio except that patients usually take Revatio three times a day at lower doses.

Our recent publication synthesized the evidence for multiple treatments for PAH. We looked at combinations of sildenafil or another drug in the same class – such as tadalafil (brand name Cialis) or vardenafil (brand name Levitra) – with another commonly used PAH drug.

The results showed that the number of clinical worsening events such as disease progression or hospitalization was reduced by 12.7% compared to placebo. Exercise capacity markers, measured by a six-minute walk test, also improved by almost 50 meters.

Evidence of sildenafil in IPF

The use of sildenafil in IPF is much less certain, as there have been few randomized controlled trials, which are considered the gold standard of evidence. Only four trials have investigated its use in IPF. A meta-analysis of this small number approached statistical significance, suggesting that the benefits would become evident if more trials were carried out.

The most recent European Respiratory Society/American Thoracic Society guidelines addressing the issue recommended against the use of sildenafil in IPF due to a lack of data.

However, recently a drug (treprostinil) that acts similarly to sildenafil has shown promise in patients with combined interstitial lung disease (an umbrella term for lung disease that includes IPF) and pulmonary hypertension. . The greatest effect seen in patients with diagnosed interstitial lung disease.

This further demonstrates the potential promise of drugs like sildenafil or similar vasodilation mechanisms in the management of IPF.

why it matters

For conditions like PAH or IPF that are incurable, repurposing drugs like sildenafil has merit. On the one hand, it is very expensive to develop new drugs. On the other hand, there is more concern about the safety of new drugs; Since Viagra is widely used, the side effect profile is well known in the medical community.

For example, sildenafil is known to cause low blood pressure and should be avoided in people with conditions that make them susceptible to low blood pressure or taking specific high blood pressure medications. Other common side effects include, but are not limited to, flushing, headaches, and vision changes.

Although sildenafil is not the magic pill for all lung diseases, it clearly has promising uses that go beyond erectile dysfunction.The conversation

Tyler Pitre, MD (Internal Medicine Physician), McMaster University; Dena Zeraatkar, Assistant Professor, Health Research Methods Evidence and Impact and Anesthesiology, McMaster University, and Jasmine Mah, MD (Internal Medicine Resident) and PhD Candidate (Geriatrics Emphasis), Dalhousie University. This article is republished from The Conversation under a Creative Commons license. Read the original article.

Share.

Comments are closed.