For severe frostbite, the United States currently offers a medication. How does it operate?

In the worst situations, frostbite can result in the death of tissues in the nose, fingers, toes, and other extremities, necessitating amputation. American physicians now have a means of protecting their patients from these potentially fatal consequences.

February was when the U.S. The first drug in the nation for treating severe frostbite was licensed by the Food and Drug Administration. Iloprost, the medication, significantly decreased amputations in almost all of the frostbite patients who took it in a clinical trial.

While only a few thousand Americans suffer frostbite each year, it is a serious worry for those who must spend a lot of time outside in the cold, such as mountain climbers, members of the armed forces, and homeless people.

Iloprost, a synthetic medication marketed under the trade name Aurlumyn and initially developed in Germany in the 1980s, is administered intravenously. It opens blood arteries, enhances blood flow, and lowers the risk of blood clotting since it functions as a vasodilator. It was mostly used to treat conditions related to blood pressure as well as Raynaud’s disease, an ailment that results in the narrowing of blood vessels in the fingers and toes.

The first investigation into whether the medication would possibly be able to free blocked blood vessels caused by frostbite was published in 1994. Five patients underwent testing, and in every instance, the frostbitten digits were successfully restored.

Subsequent research on the medication in England, France, and Nepal revealed encouraging outcomes. Patients who were rescued from high altitudes were randomly allocated to receive treatment with either iloprost, buflomedil (an additional vasodilator), or iloprost plus a medication that dissolves blood clots in the clinical trial that the FDA used in approving iloprost. According to a 2011 study published in the New England Journal of Medicine, out of the 47 patients treated over a 12-year period, none of the 16 patients who took iloprost alone required finger amputation. By contrast, amputations were required for nine out of fifteen patients in the buflomedil group and three out of sixteen patients in the iloprost combo group.

Iloprost has been a recognized treatment for frostbite for many years in several European nations as well as other countries. Science News spoke with Chris Imray, a vascular surgeon at University Hospitals Coventry & Warwickshire in England who has been using this medication to treat patients for over ten years, about the effects of frostbite on the body, the medication’s mechanism of action, and the implications for patient care in the US. The interview has been condensed to improve clarity and duration.

SN: How does frostbite affect the body physiologically?

Imray: After a few hours of exposure to the cold, frostbite is a thermal injury that primarily affects the hands, feet, nose, ears, and occasionally the external genitalia. The blood flow through the tissue slows down when the temperature falls to about 0 degrees Celsius. The next condition is thrombosis, which is the formation of clots inside blood arteries, which ultimately results in the tissue’s inability to get oxygen. After some time, the tissue dies and you develop gangrene.

SN: How did researchers come to understand that treating frostbite may benefit from focusing on blood clotting?

Imray: You could try warming the tissue to treat it if it has been harmed by a thermal injury and has a low blood supply. The difficulty is that, even though the tissue may warm up if there is no blood flow, the tissue’s ability to get oxygen will be disrupted, which will further hasten its degeneration.

We’ve long known that in certain circumstances, such as stroke or acute coronary syndrome, blood can be restored in four to six hours, which will allow the blood flow to be restored, clogs in the small blood arteries to be cleared, and oxygen to the tissues to be supplied once more. Thrombolytic drugs were used as one of the treatments for acute coronary syndrome in order to dissolve the clot. However, administering thrombolytic drugs to a patient who has had an accident and has soft tissue or skeletal injuries could increase bleeding. Instead of acting as a lytic agent on the clot, isoprost acts as a vasodilator. That’s actually kind of the origin of it.

SN: How has iloprost altered the way that frostbite is treated?

Imray: A sympathectomy was something we used to perform. In order to open up the blood vessels leading to the hands or feet, vascular surgeons would slice the sympathetic nerves. When [iloprost] was introduced, it appeared to have a comparable effect, widening blood vessels. The best part was that you didn’t have to permanently cut your nerves.

SN: How is the medication iloprost given?

Imray: The medication enters the body through the vein and travels throughout it. Usually, we begin with a low dose and raise the infusion rate gradually until the patient begins to experience side effects, such as low blood pressure, increased heart rate, or flushing of the face. We then wind it back very slightly, just enough to eliminate the symptoms. We then run it for six hours, and we do this five days in a row. To determine whether there is an improvement in the blood circulation to the tissues, imaging studies might be performed. Subsequently, the surgeons will have to deal with tissues that have been revived from near death. Overall, there is a very impressive dramatic rescue rate for limbs and fingers.

SN: How is iloprost administered?

Several processes have been proposed to explain it. Vasodilation is one. One is that it appears to have a minor effect on clotting. Additionally, it alters the red blood cells’ [ability] to pass via tiny channels.

SN: When treating frostbite, when is timing most important?

Imray: The speeds at which tissues burn energy vary. Because of the brain’s extremely high metabolic rate, there is only a brief window of time—roughly six hours—to dissolve blood clots in stroke victims. The heart is somewhat longer. The person will suffer irreversible tissue damage if you are unable to reach them in that time frame.

The tissues in the hands, feet, and muscles are largely unknown. We believed that the longest amount of time [after frostbite injury] that could be spent using iloprost was [within] 24 hours, but other patients have reportedly used it for up to five days. However, the consequences will become less noticeable the longer you wait for the particular injury.

SN: Who will gain the most from this new approval?

Imray: A lot of well-known climbers have suffered from [frostbite] injuries, and they were informed there was nothing that could be done for them. And then they started losing tissue. Therefore, our goal is to locate hospitals [near the large mountains] that have iloprost available so that, in the event of an injury, you can be transported there as soon as feasible.

Homeless persons are also affected by frostbite. They may not cause as much concern as the well-known climbers, but they nonetheless run the risk of suffering life-threatening frostbite injuries and amputations.

People who would be in danger of losing limbs will be affected by [the iloprost approval]. Although it took a while for the FDA to approve it, I’m happy that it has.