In serious cases, frostbite can damage body tissues like fingers, toes, and noses, sometimes leading to amputation. But now, doctors in the United States have a solution to help prevent these severe consequences.
In February, the U.S. Food and Drug Administration approved the first medication in the country for treating severe frostbite. In a test with patients, the drug called iloprost significantly lowered the need for amputations in almost all the frostbite cases.
Though frostbite isn’t very common in the U.S. — affecting only a few thousand people each year — it’s a big worry for those who spend a lot of time outside in cold conditions, like mountain climbers, military personnel, and homeless individuals.
Iloprost, originally made in Germany in the 1980s and sold as Aurlumyn, is a synthetic drug given through injection. It works by widening blood vessels, improving blood flow, and preventing blood clots. Initially, it was used to treat Raynaud’s disease, which narrows blood vessels in fingers and toes, and blood pressure issues.
In a study from 1994, researchers tested if iloprost could also help with frostbite by opening blocked blood vessels. They tried it on five patients and found that it successfully healed their frostbitten fingers and toes.
The drug showed good results in studies conducted in England, France, and Nepal. In one study, patients rescued from high altitudes were given different treatments, including iloprost alone or combined with a clot-busting drug. None of the patients treated with iloprost alone needed amputations, compared to some patients in the other treatment groups.
Iloprost has been approved as a frostbite treatment in many European countries and other parts of the world for several years. Science News interviewed Chris Imray, a vascular surgeon in England who has been using this drug for over a decade, to understand how frostbite affects the body, how the drug works, and its implications for patient treatment in the United States.
SN: What happens to the body during frostbite?
Imray: Frostbite is an injury caused by extreme cold, affecting areas like the hands, feet, nose, ears, and sometimes even genitalia after prolonged exposure to cold. When tissue temperature drops to around zero degrees Celsius, blood flow slows down, leading to clot formation in blood vessels and reduced oxygen delivery to the tissue. This lack of oxygen causes tissue damage and eventually tissue death, known as gangrene.
SN: How did scientists discover that targeting blood clotting could help in frostbite treatment?
Imray: When tissue is damaged from extreme cold and has poor blood flow, warming it may not help because it won’t restore oxygen delivery. This can actually worsen the condition. In situations like stroke or heart attacks, restoring blood flow quickly is crucial to prevent tissue damage. Thrombolytic agents are sometimes used to dissolve blood clots, but they can cause bleeding in patients with certain injuries. Iloprost works differently—it widens blood vessels instead of breaking down clots. This is why it’s considered for frostbite treatment.
SN: How has iloprost changed frostbite treatment?
Imray: Before iloprost, surgeons would perform a sympathectomy, cutting nerves to improve blood flow to the hands or feet. Iloprost works similarly by widening blood vessels without the need for surgery.
SN: How is iloprost given?
Imray: It’s given through an IV, gradually increasing the dose until the patient shows side effects like flushing or changes in heart rate or blood pressure. Then, we adjust the dose to alleviate the symptoms. The infusion runs for six hours a day for about five days. Imaging tests help us see if there’s improvement in blood supply to the tissues. Surgeons then manage the affected tissues, leading to a significant rate of limb and digit preservation, which is impressive.
SN: How does iloprost work?
Imray: There are a few ways it might work. It can widen blood vessels, affect clotting a bit, and help red blood cells move through small vessels.
SN: What’s the important timing for treating frostbite?
Imray: Different body tissues have different speeds at which they get damaged. The brain gets damaged quickly, so there’s only about six hours to treat a stroke. The heart can last a bit longer. But if you wait too long, the damage can be permanent.
We’re not exactly sure about tissues in the hands, feet, and muscles. It was believed that 24 hours was the maximum time after frostbite for using iloprost, but some cases have shown it can still work up to five days later. However, the longer you wait, the less effective the treatment might be.
SN: Who will benefit most from this new approval?
Imray: Many high-profile climbers have faced frostbite injuries and were told there’s nothing that can be done, resulting in tissue loss. We aim to set up medical units near big mountains where iloprost can be administered quickly after an injury.
Homeless individuals are also affected by frostbite, though their cases often don’t receive as much attention. They can suffer serious injuries leading to life-changing amputations.
The approval of iloprost will be transformative for those at risk of losing limbs. While I’m pleased with the FDA’s approval, it took quite a while to get there.
