Study shows promise for oral snakebite remedy

Researchers at Liverpool School of Tropical Medicine (LSTM) have completed a phase I clinical trial of a new oral agent for the treatment of snakebites.

The study, conducted by scientists from LSTM’s Center for Snakebite and Medical Interventions and the Kenya Medical Research Institute (KEMRI) and published in the journal eBioMedicine, shows that Unithiol, which is already used in medical practice, is safe, well tolerated and easily administered in remote rural clinics, paving the way for its development as an off-the-shelf treatment.

Unithiol is approved for the treatment of heavy metal poisoning, but was selected for study in the treatment of snakebite due to its ability to neutralize snake venom metalloproteinases. These components of zinc-based toxins, found in the venoms of vipers and many other snakes, cause severe tissue damage and life-threatening bleeding in snakebite patients.

Snakebites remain a serious global health problem, causing more than 140,000 deaths per year, mostly in rural areas of sub-Saharan Africa, Latin America and Asia. Existing drugs for treatment are expensive, can cause serious side effects and must be administered intravenously in a hospital setting, delaying life-saving treatment.

Dr. Michael Abouyannis, lead author of the study and clinical research fellow at LSTM, said: “The animal-based anti-venom drugs used today are based on 100-year-old principles. The fact that these outdated treatments are still in use suggests that snakebite is not considered a public health problem. Low molecular weight drugs such as unithiol may be safer and cheaper and can be easily taken in pill form.

This phase 1 trial showed that unithiol is safe even at the high doses we believe would be required to treat snakebite, so we may be on the cusp of bringing snakebite treatment into the 21st century and significantly improving patient outcomes.”

Preclinical studies by LSTM scientists have previously shown that unithiol can prevent the worst effects of poison and potentially save lives. The Phase 1 clinical trials evaluated various doses of unithiol in oral and intravenous forms. All showed no serious side effects, even at the maximum dose, and blood tests on participants showed that the drug was rapidly absorbed and present in the blood at concentrations that should inhibit snake venom toxins.

Based on these results, the LSTM team will move unithiol into a Phase II clinical trial, where the drug will be tested on snake-bitten patients who have undergone venom poisoning. If successful, unithiol could be rapidly introduced into rural clinics and primary care facilities, allowing snakebite victims to buy time to get to hospital and reduce the severity of the effects of the bite.

Professor Nicholas Casewell, Director of CSRI at LSTM, said: “Snakebites often occur in remote rural areas where it can take hours to get to the nearest hospital. As we move into Phase 2 clinical trials of unithiol, we are moving closer to a world where snakebite treatment can be provided at a clinic just a few minutes’ drive from the patient.”

“While unithiol cannot be a stand-alone treatment, we hope it will prevent the worst effects of snakebite and allow victims to gain time to get to hospital, thereby reducing the risk of death or disability.”

The development of safe, affordable and easy-to-administer treatments such as oral medications could play a critical role in achieving the World Health Organization’s (WHO) goal of halving death and disability from snakebites by 2030. Assessing their safety and efficacy in such trials represents a critical step towards achieving this goal.

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Published: 14.03.2025

Updated: 13.03.2025

Medical author, Medical editor:

Stepan Yuk

Medical expert:

PhD. Olexandr Voznyak