The cure for North American coral snake bite is about to disappear. Why an unprofitable anti-venom may end up costing lives.
By Glenn Derene
As venomous snakes go, the coral snake is a clumsy biter. Unlike pit vipers such as rattlesnakes and cottonmouths, which have gruesomely efficient fangs that articulate forward during a strike and inject venom like hypodermic needles, the brightly colored coral snake has small, rear-facing fangs that guide venom into a wound. This process doesn't always work well--experts estimate that 25 percent of coral snake envenomations are dry bites--which is perhaps why the coral is so unaggressive. The snake is found throughout Florida, as well as in parts of Alabama, South Carolina, Louisiana, Texas and Arizona, but there are generally only about 100 or so bites each year.
What the coral lacks in belligerence, it makes up for in neurotoxicity. Unlike bites from pit vipers, which cause immense pain and swelling at the wound site, coral snake victims usually report little pain after being bitten. But the effects begin to show within hours, with symptoms such as tingling sensations in the extremities, dysarthria (slurred speech) and ptosis (droopy eyelids). Then a victim's lungs shut down. "The venom acts as a neuromuscular blockade to the lungs," University of Florida professor of medicine Craig Kitchens says. "Without antivenom, you need artificial respiration or you die."
Unfortunately, after Oct. 31 of this year, there may be no commercially available antivenom (antivenin) left. That's the expiration date on existing vials of Micrurus fulvius, the only antivenom approved by the Food and Drug Administration for coral snake bites. Produced by Wyeth, now owned by Pfizer, the antivenom was approved for sale in 1967, in a time of less stringent regulation.
Wyeth kept up production of coral snake antivenom for almost 40 years. But given the rarity of coral snake bites, it was hardly a profit center, and the company shut down the factory that made the antivenom in 2003. Wyeth worked with the FDA to produce a five-year supply of the medicine to provide a stopgap while other options were pursued. After that period, the FDA extended the expiration date on existing stock from 2008 to 2009, and then again from 2009 to 2010. But as of press time, no new manufacturer has stepped forward.
Antivenom shortages are a surprisingly common occurrence. The entire state of Arizona ran out of antivenom for scorpion stings after Marilyn Bloom, an envenomation specialist at Arizona State University, retired in 1999. Bloom had been single-handedly making all the scorpion antivenom for state hospitals. Recently, Merck & Co, the only FDA-licensed producer of black widow antivenom, has cut back distribution because of a production shortage of the drug. In a 2007 report, the World Health Organization listed worldwide envenomations as a "neglected public health issue."
New scorpion and black widow antivenoms are currently in the pipeline, thanks to efforts by several poison-control associations to speed foreign drugs into the market through FDA research programs. There is also a coral snake antivenom produced by Mexican drug manufacturer Instituto Bioclon that researchers believe could be even more effective and safe than the outgoing Wyeth product. But that drug, Coralmyn, is not currently licensed for sale by the FDA. The tests required for licensing would cost millions of dollars, and for such a rare treatment (there are 15 times as many scorpion stings per year as coral snake bites), it could take decades for Bioclon to make its money back.
Envenomation experts express exasperation and disbelief at the situation. "It's ridiculous that we're losing a technology that we already have," says Joe Pittman, a snakebite treatment specialist at the Florida Poison Information Center in Tampa. "It's even more ludicrous that we have a product that's available, and we have to jump through so many hoops to get it approved." In July 2009, an FDA advisory board determined that Coralmyn qualified for an accelerated approval process, but there is still no one with the estimated $3 million to $5 million to pay for the required studies.
"Nobody in this situation is being a bad actor," says Eric Lavonas of the Rocky Mountain Poison and Drug Center. "We just don't have a system set up to deal with it." With no adequate replacement for coral snake antivenom, hospitals are likely to appeal to local zoos, many of which maintain small stocks for their staff. But zoos are under no obligation to provide the medicine.
If and when shortages do occur, many hospitals will have no other option but to intubate coral snake bite victims on ventilators for weeks until the effects of the toxin wear off--potentially costing hundreds of thousands of dollars per bite. "It's probably going to end up costing us far more not to deal with this than to deal with it," Lavonas says, "both in human suffering, and in dollars and cents."