Scientists find that a common blood-thinning drug neutralises cobra venom
Medication.
Scientists from the University of Sydney and Liverpool School of Tropical Medicine have discovered that a common blood-thinning drug can be repurposed as an antidote for cobra venom.
The drug, Heparin, is set to become a cheap antidote to cobras which kill thousands of people globally per year and maim others.
In Kenya, data from the Institute of Primate Research (IPR) shows that about 20,000 people are bitten by snakes annually. Out of this, about 4,000 result in fatalities while 7,000 result in paralysis or other health complications.
In the research published in the Science Translational Medicine, the scientists based in Australia, Canada, Costa Rica and the UK, showed that the drug can stop the necrosis- death of most or all of the cells in an organ or tissue- caused by cobra bites.
The team employed CRISPR gene-editing technology to identify the human genes essential for cobra venom to induce necrosis, which destroys the flesh around the bite.
They discovered that the venom targets enzymes necessary for producing the related molecules heparan and heparin, which are produced by many human and animal cells.
Antidote
Heparan is found on the cell surface, while heparin is released during an immune response. Due to their similar structures, the venom can bind to both molecules. Leveraging this knowledge, the team developed an antidote that can prevent necrosis in human cells and mice.
Unlike current anti-venoms for cobra bites, the drug acts as a 'decoy' antidote. By inundating the bite site with 'decoy' heparin sulfate or related heparinoid molecules, the antidote can bind to and neutralize the venom toxins that cause tissue damage.
The scientists believe that the new discovery will reduce injuries resulting from necrosis and slow down the action of the venom, thus improving survival rates of cobra bite victims.
"Biological agents like venoms and toxins all require some collaboration from the host side, the human side, so our study was to identify what, in humans, interacts with the venom to create this necrosis and death. What we’re finding is when we take different venoms from very different species, there’s a small number of ways they interact with human cells, said Senior study author Professor Greg Neely, from the University of Sydney.
"One of the cool things from a science perspective is that we think we can identify four or five different ways that venoms as a whole interact with cells - and then we can make universal antidotes that can block big groups of species. We hope that the new cobra antidote we found can assist in the global fight to reduce death and injury from snakebite in some of the world’s poorest communities," he added.
His counterpart, Tian Du, the lead author explained that the drug used is inexpensive, readily available and listed as an essential medicine by the World Health Organisation. Thus, the drug, after human clinical trials, can be quickly rolled out as a cheap, safe and effective drug to treat cobra bites.
"Snakebites remain the deadliest of the neglected tropical diseases, with its burden landing overwhelmingly on rural communities in low- and middle-income countries.
"Our findings are exciting because current antivenoms are largely ineffective against severe local envenoming, which involves painful progressive swelling, blistering and/or tissue necrosis around the bite site. This can lead to loss of limb function, amputation and lifelong disability,” said Prof Nicholas Casewell, a co-author from Liverpool School of Tropical Medicine Centre for Snakebite Research and Interventions.
According to Drugbank, Heparin is used to prevent and treat blood clots in blood vessels and the heart. It also states that this drug is not absorbed through the gastrointestinal tract and is therefore administered intravenously. The highest concentration of the drug in the bloodstream is typically achieved immediately after intravenous administration.
The University of Nairobi Research Archive states that: “Heparin remains the most widely used parenteral anti- thrombotic drug. It is a high risk medicine that may cause significant harm including death if not used properly. Heparin has low therapeutic index and is ranked among the top 5 “high alert” medications by the Institute of Safe Medication Practices.”
It adds: “Heparin-related medication errors can occur at any stage from prescribing, dispensing, administration to monitoring of therapy. Its use should therefore be monitored to prevent possible errors and maximize benefits of use.”
Other medical sites warn against the drug being combined with aspirin and non-steroidal anti-inflammatory drugs as it increases the risk of haemorrhage. It is also not recommended for use at the end of pregnancy due to risk of haemorrhage during delivery.
An online spot-check shows that online pharmacies sell 5ml of the drug at around Sh844, while hospitals sell the same at around sh115.
Sale of the drug is prohibited unless a valid prescription from a registered medical practitioner is provided.
