Time is the enemy for people who have been bitten by a poisonous snake, but a new study may give them a little more from him. The researchers identified an ointment that slows the spread of certain types of snake venom through the body, which could give snakebite victims longer to reach a hospital or clinic.
While venomous snakes kill only a handful of people in the US each year, the World Health Organization puts the overall balance to about 100,000 people. When some snakes strike, the large proteins in their venom seeping blood immediately but meander through the lymphatic system to the heart. In Australia, a country with slithering snakes harmful, first aid recommended for a bite includes tightly wrap the bitten limb to close the vessels-a method called lymphatic compression bandage with immobilization (PBI). The idea is to hinder the spread of venom until the victim can receive antivenom medicine, mainly on antibodies that block and neutralize the poison. But PBI is not practical if the bite is on the chest or face, and one study found that even people trained to perform the technique are good only about half the time. As a result, some people do not receive antivenin in time.
So physiologist Dirk van Helden of the University of Newcastle in Australia and his colleagues went in search of a chemical method to retain the poison. They settled on an ointment containing nitroglycerin, best known compound such as nitroglycerin that doctors used to treat everything from tennis elbow to angina. The ointment prescribed for a painful condition called anal fissures, releases nitric oxide, which causes the lymph vessels to clench. Researchers first injected volunteers in the foot with a harmless radioactive mixture which, as some snake toxins, moves through the lymphatic vessels. In control subjects who did not receive the ointment, the mixture took 13 minutes to climb to the top of the leg. But it took 54 minutes if the researchers immediately smeared the ointment around the injection site, reports the online team today Nature Medicine .
To determine whether the ointment improvement of survival, the researchers injected the feet of anesthetized rats with venom of eastern brown snake, a cobra on is one of the deadliest Australia, and measured how time elapsed before the rodents stopped breathing. Rats lived about 50% longer if the researchers slathered hind rodents with cream.
Although the team can not specify the number of minutes or hours the treatment might buy, the results suggest that "it gives you the time and a half to get help," said van Helden. "I'd rather just time." He said that hikers and people who work in rural areas might consider carrying the cream if they are bitten when they are far from medical facilities.
the method is "very exciting," says Steven Seifert, medical director of the New Mexico Poison and Drug Information Center in Albuquerque. "It makes sense to try to slow the passage of venom into the circulation." toxicologist medical Eric Lavonas, associate director of the Rocky Mountain Poison and Drug Center in Denver, Colorado, is also impressed. "This is very promising," he said. The authors "have good studies to evaluate this approach."
Yet Seifert and Lavonas whether such treatment would do much good in the US. Australian snakes largely inject neurotoxic venom that spreads through the body and attacks the nervous system, causing paralysis. The authors of most US snakebites are rattlesnakes, copper and cottonmouths, which inject a different type of venom that destroys the tissue mainly near the bite. But the researchers note that the ointment could be useful in many other countries inhabited by dangerous snakes, such as cobras, mambas and kraits, that produce neurotoxic venom. "If this treatment pans out, it can revolutionize first aid for snakebite in parts of the world where the venom causes paralysis," says Lavonas.
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