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June 27, 2011 -- A new ointment may buy precious time for snakebite victims by slowing the flow of snake venom through the body.
Researchers found that the ointment increased the survival time of rats injected with snake venom by about 50%.
The ointment contains the drug glyceryl trinitrate, which is used in the treatment of heart failure. It works by delaying the transit of snake venom through the lymphatic system.
When used as part of first aid for snakebites, the ointment could give snakebite victims in remote areas, such as hikers and campers, extra time to get medical care and antivenom treatment.
Researchers say snakebites account for about 100,000 deaths and 400,000 amputations worldwide annually.
“Many snake venoms contain large toxin molecules that cannot enter the bloodstream directly but are absorbed and transported by the lymphatic vessels before entering veins near the heart,” researcher Megan E. Saul of John Hunter Hospital in New Lambton, New South Wales, Australia, and colleagues write in Nature Medicine.
First aid for snakebites involves attempting to mechanically block the flow of snake venom with pressure bandages and pads.
But in this study, researchers looked at whether using a drug to slow the flow of snake venom to the heart might have a similar effect.
They treated rats injected with snake venom with the ointment and found it increased their survival time by about 50% by slowing the transport of the snake venom through the lymphatic system.
In a second experiment, the ointment was applied to human volunteers along with a benign substance that allowed researchers to monitor its flow. They found the ointment slowed the flow of the substance through the lymphatic system in the same way.
Researchers say the results suggest that use of glyceryl trinitrate in ointment form could be a new option in first aid for snakebites and increase the time available to obtain an antidote.