Coral Snake (Micrurus sp) bites in North America are relatively rare. The last person to die from a coral snake bite in the USA was in 2006 when the victim did not seek treatment quickly because he was intoxicated. A second person bitten by the same snake survived the bite because he sought treatment and received the antivenom. The most recently made batch (Lot 403002) of North American coral snake antivenom was set to expire at the end of October 2010, but the U.S. Food and Drug Administration has extended the date to October 31, 2011 in the hope that another source of the antivenin can be found. On October 22, 2010 the FDA sent a note to health-care workers that contains the following statement.
"FDA has extended the expiration date on this lot of Antivenin (Micrurus fulvius) (Equine). The extension is based upon FDA evaluation of stability data, which determined that this lot of product will maintain stability and potency for an additional year.
Wyeth Pharmaceuticals no longer manufactures Antivenin (Micrurus fulvius) (Equine). There is no alternative product licensed in the U.S. for coral snake envenomations. Lot 4030026 is labeled with an expiration date of October 31, 2008. Because this lot has a new expiration date, you may continue to maintain the product in your inventory and keep it available for use until October 31, 2011. The manufacturer is updating the current labeling through a Dear Health Care Provider Letter.
Lot 4030026 continues to be available. Wyeth is closely managing their inventory, and will supply product only to direct customers."
According to Sánchez, et al. (2008) coral snake bites compose less than 2% of total snakebites in most countries from southeastern United States to Argentina. In 2006, Wyeth Pharmaceutical notified customers that the production of the North American coral snake antivenin (NACSA) in the US was discontinued and adequate supplies were available to meet historical needs through the end of October 2008. They suggest that the logical alternative to replace the Wyeth product is the coral snake antivenom, Coralmyn, produced by the Mexican company, Bioclon. Sánchez et al. compared neutralization between the Wyeth and Coralmyn antivenoms with the North American coral snake venoms, the venom lethal doses (LD50) and antivenom effective doses (ED50) were determined in 18–20 g, female mice. They found Coralmyn antivenom was able to effectively neutralize three LD50 doses of all venom from both Micrurus tener tener and Micrurus fulvius fulvius, while the Wyeth antivenom only neutralized M. f. fulvius venom and was not effective in neutralizing three LD50 doses of M. t. tener venom. Therefore, Coralmyn is effective in the neutralization of both clinically important coral snake venoms in the USA.
Unfortunately, Bioclon has estimated it would take more than $5-10 million to research a new synthetic antivenom. Thus it would be cost prohibitive due to the small number of coral snake bites each year. This situation is just one more example of the dysfunctional nature of the American heatlthcare system.
Sánchez, E. E., J. C. Lopez-Johnston, A. Rodríguez-Acosta and J. C. Pérez. 2008. Neutralization of two North American coral snake venoms with United States and Mexican antivenoms. Toxicon 51:297-303.