A drug to treat frostbite is finally available

The conversationFrostbite can occur at temperatures just below freezing (-0.55°C), although frostbite at such temperatures is usually mild and will not cause permanent damage. But what happens if you live and work somewhere where it gets much colder?

As a Canadian, I’m used to seeing news reports during cold snaps warning people not to go outside because frostbite is possible “in a minute.”

To date, there are no approved therapies for severe frostbite. But on February 14, 2024, the U.S. Food and Drug Administration (FDA) announced that it had approved the first-ever anti-freeze drug.

Frostbite is evolution’s response to prolonged or extreme cold, which constricts blood vessels and slows blood flow in the extremities. This keeps the blood flowing in the vital organs, increasing the chance of survival in the extreme cold.

The downside is that this can result in permanent damage to the fingers, toes and parts of the face, sometimes requiring amputation of the affected body parts. (Frostbite has resulted in some strange traditions, such as the Sourtoe Cocktail in Dawson City, where customers drink a cocktail containing an amputated frozen toe.)

Reused medicine

The new drug, called iloprost (brand name Aurlumyn), is being given a new purpose. This means that it was not originally developed to treat frostbite. In this case, it is used to treat high blood pressure in the lungs.

Repurposed drugs have already passed important (and expensive) safety tests and are therefore much cheaper (about $40-80 million or £32-64 million) to develop for additional medical problems than creating a new drug (about 1- $2 billion). ), making drug repurposing an attractive way to find new treatments.

Many medications have been tried as possible treatments for severe frostbite. However, iloprost is the first to undergo a clinical trial, where patients with severe frostbite were randomly assigned to receive iloprost or not.

The study found that 60 percent of patients who did not receive iloprost had injuries severe enough to warrant amputation, compared with 0 percent of patients who received iloprost.

Although the total number of patients tested in this study was small at 47, the combined facts that there are no other approved pharmaceutical treatments for freezing and the impressive number-saving results found in this randomized human trial were enough to convince the FDA to approve this approve. reused therapy for severe frostbite.

How it works

Iloprost works by expanding patients’ blood vessels (called a vasodilator) and preventing the formation of blood clots. Because freezing causes narrowing of blood vessels, this suggests that one mechanism by which iloprost helps heal frozen tissue is to reverse this narrowing.

However, when blood flow is reintroduced to such tissue, it can paradoxically worsen the injury and cause more damage. This is called ‘reperfusion damage’ and is largely caused by a sudden influx of oxygen that causes oxidative stress. Interestingly, in addition to being a vasodilator, iloprost also reduces oxidative stress, suggesting that this dual mechanism of action could help explain its impressive potential as an anti-freeze treatment.

Frostbite is a common condition in colder parts of the world. A Finnish study shows that 1.1 percent of the Finnish population suffers from severe frostbite each year and 12.9 percent suffers from mild frostbite. Because frostbite injuries can be serious, the approval of a drug that significantly reduces the risk of life-altering amputations of patients’ fingers, toes and noses will certainly be welcome news to many.

An unintended consequence, however, could be that the Sourtoe Cocktail Club will have a harder time finding new frozen toes to add to its collection in the coming years.

Steven R. Hall, lecturer in pharmacology, Lancaster University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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