Friday, July 29, 2011

New Snakebite Treatment

Scientists in Australia developed a new ointment to treat snakebites to buy time until the patient is adequately treated. Applying a nitric oxide–containing ointment near the bite site slows the spread of different types of snake venom, which include the notorious eastern brown snake’s. This treatment might make all the difference between dying on the road and getting to the hospital in time. Physiologist Dirk van Helden at the University of Newcastle and his colleagues showed that in humans, applying an ointment containing nitric oxide within one minute of a simulated snakebite slows the transit of injected tracer molecules. Foot-to-groin venom travel times increased from an average of 13 minutes without the ointment to an average of 54 minutes with the ointment applied in a 5-centimeter diameter circle just up the limb from the bite site.

The nitric oxide source in the ointment is glyceryl trinitrate, the same compound used to treat angina. When applied to the body, the ointment releases microscopic amounts of nitric oxide gas, which sink through the skin. There, the gas inhibits pumping of the lymphatic vessels — the primary roadway for molecules too big to squeeze through blood vessel walls and hitch a ride through the bloodstream. But victims might be out of luck if bitten by a Black Mamba or cobra, since the ointment isn’t effective against venom containing smaller toxic proteins capable of directly entering the bloodstream. Another potential snag is the need for bite victims to be quick on the draw. The scientists applied ointment within 20 seconds of snakebite in rats and within a minute in the human subjects.