Cobra venom neutralized by widely used blood-thinning drug Heparin

A team of scientists from Australia, Canada, Costa Rica and the United Kingdom has discovered that a drug typically prescribed to thin the blood can be used as a cheap antidote to cobra venom.

Snakebites kill about 138,000 people each year, mainly in poorer rural areas in low- and middle-income countries in Africa, South and Southeast Asia.

In more than 400,000 others, necrosis occurs, in which the tissue around the bite dies and turns black.

Cobras are responsible for most bites in parts of Africa and India. And heparin can neutralize the necrosis-causing toxins in the venom of some spitting cobras.

The drug is not effective against all snake venoms, but scientists say it could be cheaper and more flexible than existing antivenoms, many of which only work against one species of snake and cannot prevent necrosis.

Now that the drug has been tested on mice, trials will now also be conducted on humans.

Senior author of the study, Prof Greg Neely, from the University of Sydney, said: “Our discovery could dramatically reduce the horrific necrosis injuries caused by cobra bites – and it could also slow venom production, which could improve survival rates.

“Biological agents such as venom and toxins all require some cooperation from the host, the human side. Our research was therefore aimed at identifying what interacts with the venom in humans and causes this necrosis and death.

“What we find is that when we use different types of venom, there are a number of ways in which they interact with human cells.

“One of the cool things from a scientific perspective is that we think we can identify four or five different ways that venom as a whole interacts with cells, and that allows us to make universal antidotes that can block large groups of species.

“We hope that the new cobra antivenom we have found can contribute to the global fight to reduce deaths and injuries from snakebites in some of the world’s poorest communities.”

Lead author, PhD candidate Tian Du, also from the University of Sydney, called it a major step forward.

“Heparin is cheap, ubiquitous and on the World Health Organization’s list of essential medicines,” she said.

“After successful human trials, it could relatively quickly become a cheap, safe and effective drug for treating cobra bites.”

Another scientist, head of the Liverpool School of Tropical Medicine Centre for Snakebite Research and Interventions, Professor Nicholas Casewell, said: “Snakebite remains the deadliest of the neglected tropical diseases, with the greatest burden borne by rural communities in low- and middle-income countries.

“Our findings are promising because current antivenoms are largely ineffective against severe local envenomation, 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.”