A drug normally prescribed to thin the blood can be used as a cheap antidote to cobra venom, a team of scientists from Australia, Canada, Costa Rica and the UK has found.
Snakebites kill about 138,000 people each year, mostly in poor rural areas of low- and middle-income countries
in Africa, South and Southeast Asia. More than 400,000 more people develop necrosis, when the tissue around the bite dies off and turns black. Cobra bites are most common in parts of Africa and India.
Heparin can neutralize the necrosis-causing toxins found in the venom of some spitting cobras.
The drug is not effective against all types of snake venom, but researchers say it may be cheaper and more flexible than existing antivenoms (antidotes against the bites of venomous snakes, spiders and scorpions), many of which work only against one species of snake and cannot prevent necrosis.
After testing the drug on mice, the next step will be human trials.
Global struggle
Senior study author Professor Greg Neely from the University of Sydney says: "Our discovery may significantly reduce the horrific injuries from necrosis caused by cobra bites, as well as slowing the effects of the venom, which may increase survival rates."
Biological agents such as poisons and toxins require a certain interaction on the part of the host, the human, so the study by a group of scientists had to determine what in the human body interacts with the poison to cause necrosis and death.
"We found that when we take different poisons from different animal species, they interact with human cells in a small number of ways," says Prof. Neely. "From a scientific perspective, one of the interesting things is that we think we can identify four or five different ways that poisons in general interact with cells, and then we can create universal antidotes that can block large groups of species."
Researchers hope the new cobra antidote found will help in the global fight to reduce snakebite deaths and injuries in the world's poorest communities.
Lifetime disability
The study's lead author, PhD student Tian Du, also from the University of Sydney, called it a big step forward.
"Heparin is inexpensive, ubiquitous and on the World Health Organization's list of essential medicines," she says. "After successful human trials, it could be distributed relatively quickly to become a cheap, safe and effective drug for the treatment of cobra bites."
Another scientist, head of the Center for Snakebite Research and Intervention at the Liverpool School of Tropical Medicine, Professor Nicholas Caswell, believes snakebites remain the deadliest of the neglected tropical diseases, and their burden falls mainly on rural communities in low- and middle-income countries.
"Our results are very interesting because existing antivenoms are virtually ineffective against severe local envenoming, which includes painful progressive swelling, blistering and/or tissue necrosis around the bite site," says Prof. Caswell. "This can lead to loss of limb function, amputation and lifelong disability."