July 31, 2013
Breakthrough Snakebite Nasal Spray Could Save Thousands Of Lives
redOrbit Staff & Wire Reports - Your Universe Online
A team of California researchers has developed a novel approach to treating venomous snakebites by administering antiparalytics topically via a nasal spray, a breakthrough that could dramatically reduce the estimated 125,000 global snakebite fatalities each year.
Snakebite is one of the most neglected of tropical diseases and there is often no easy way to treat victims in the field. An estimated 75 percent of snakebite victims who die do so because they don't reach the hospital in time.
For a number of reasons, antivenoms are an imperfect solution. For example, even if the snake has been identified and the corresponding antivenom exists, venomous bites often occur in remote locations far from population centers. Furthermore, antivenoms are costly, require refrigeration and require significant expertise to administer and manage.
"In addition to being an occupational hazard for field scientists, snakebite is a leading cause of accidental death in the developing world, especially among otherwise healthy young people," said Dr. Lewin.
"We are trying to change the way people think about this ancient scourge and persistent modern tragedy by developing an inexpensive, heat-stable, easy-to-use treatment that will at least buy people enough time to get to the hospital for further treatment."
In his role as Director of the Academy's Center for Exploration and Travel Health, Lewin prepares field medicine kits for the museum's scientific expeditions around the world, and often accompanies scientists as the expedition doctor.
Two years ago, he assembled snakebite treatment kits for the Academy's Hearst Philippine Biodiversity Expedition that would have required scientists to inject themselves if they needed treatment. But after seeing the team's apprehension about the protocol, Lewin began to wonder if there might be a better way to treat snakebite in the field.
In some fatal snakebites, victims are paralyzed by the snake's neurotoxins, resulting in death by respiratory failure. A group of common drugs known as anticholinesterases have been used for decades to reverse chemically-induced paralysis in operating rooms and, in intravenous form, to treat snakebite when antivenoms are not available or not effective. However, it is difficult to administer such IV drugs outside of a hospital setting, so Lewin began to explore the idea of a different delivery vehicle for these antiparalytics - a nasal spray.
In April of this year, Lewin and a team of anesthesiologists led by Dr. Philip Bickler at UCSF Medical Center designed and completed a complex experiment that took place at the university. During the study, a healthy human volunteer was paralyzed, while awake, using a toxin that mimics that of cobras and other snakes that disable their victims by paralysis. The experimental paralysis mimicked the effects of neurotoxic snakebite, progressing from eye muscle weakness all the way to respiratory difficulty, in the same order as is usually seen in envenomation. The team then administered the nasal spray and within 20 minutes the patient had recovered.
Later that month, while Lewin was giving the keynote address at the American Society for Clinical Investigation/Association of American Physicians meeting in Chicago, he discussed the experiment and its origins. The meeting gave Lewin the opportunity to meet Dr. Stephen Samuel, an Indian physician and scientist from Trinity College Dublin who was interested in collaborating with Lewin in India, where an estimated 1 million people are bitten by snakes every year, resulting in tens of thousands of deaths.
Lewin flew to India to help Samuel set up treatment protocols at a rural hospital in Krishnagiri. In June, Samuel, Dr. CS Soundara Raj and colleagues at TCR Multispeciality Hospital in Krishnagiri, Tamil Nadu, India treated a snakebite victim using the new protocol. The patient, a 50-year-old woman, was suffering from persistent facial paralysis from a krait bite, despite having undergone a full course of antivenom treatment. Upon treatment with the antiparalytic nasal spray, the facial paralysis was reversed within 30 minutes. Two weeks later, the patient reported having returned to her daily activities.
Lewin and his US colleagues are now conducting additional studies on mice to develop new methods and drug combinations, as there are many combinations of anticholinesterases and anticholinergic agents that could be used to make delivery of the drugs more predictable through the mucous membranes in the nose or eyes.
He is also working to set up future clinical studies with Samuel, Soundara Raj and their colleagues in India.
"We have to look into designing a product, maybe stock it in the local pharmacies throughout farming areas," Samuel told Discover Magazine. "It's not going to be a substitute for antivenom but it will buy time. It should save a lot of lives."