A commonly used blood thinner can be used as an antidote to cobra venom, an international study has found, research that a Queensland expert has called “really exciting”.
In the study, published in the Journal of Science Translational Medicine on Thursday, Prof Nicholas Casewell described snakebites as the “deadliest of neglected tropical diseases, with its burden landing overwhelmingly on rural communities in low and middle income countries”.
Cobra bites are usually treated using antivenom administered through an IV drip, meaning the drug reaches the bloodstream rather than the tissue. Antivenom treatments are therefore ineffective in treating necrosis, the irreversible death of body tissue, which can lead to amputation or a loss of limb function. Treatment is also expensive, and it can take days for patients to get to a hospital.
Lead author of the study, Tian Du from the University of Sydney, said if human trials are successful, Heparin – a blood thinner that can directly reach infected tissue – could be used on-site, likely in combination with other drugs.
Du said after successful human trials, heparin, which is a World Health Organization-listed essential medicine, could be rolled out relatively quickly to become a cheap, safe and effective drug for treating cobra bites.
While she said it was unclear at this stage how much heparin will reduce tissue damage, she is hopeful that damage will be reduced by 50-100%, depending on the dosage and how quickly the drug is delivered.
WHO has announced a goal of halving the number of deaths and disability due to snakebites by 2030, having recognised snakebites as a priority among neglected tropical diseases. While the number of people bitten by cobras is unclear, cobra species account for most snakebite incidents in parts of India and Africa.
The research team analysed which genes are targeted by snake venom. They then identified these genes are responsible for producing heparan sulfate on the surface of cells, as well as heparin sulfate, which is released in an immune response. Heparin acts as a decoy antidote binding to and neutralising toxins within the venom which causes tissue damage.
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The researchers used the same method to find an antidote to box jellyfish venom in 2019, and are working on finding similar antidotes for Australian black snakes and blue bottle stings.
Associate Prof Bryan Fry, a venom expert at the University of Queensland who wasn’t involved in the study, said the research was “really exciting stuff”.
“Cobra venoms cause profound local tissue damage … it’s like you’ve injected the person with acid,” he said. “This is the first study of its type with this particular toxin class and the action that it has.”
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