Summer 2012: Toxicology Corner: Snakebite s and Antivenom

Summer 2012: Toxicology Corner: Snakebite s and Antivenom


POSTED IN: Summer 2012, Toxicology,

Written by: Evan Schwarz, Assistant Professor Division of Emergency Medicine, Medical Toxicology Washington University School of Medicine

It’s sunny and warm, which means people are taking vacations and spending more time outside, possibly camping, boating, and hiking. It also means that more people will unintentionally have encounters with snakes, and for us in the Emergency Department, we’ll be treating patients presenting with snakebites. It was not very long ago that the antivenom used to treat crotalid (rattlesnake, cottonmouth, and copperhead) envenomations had such a high rate of adverse events, that very few people received it. This was particularly true for copperhead envenomations as mortality from the bite was incredibly low and many patients did well with aggressive pain control and supportive care.

This all changed with the development of Crofab® and its approval in 2000. This newer antivenom was shown to have a much better safety profile than the older antivenom. As the rate of adverse events dramatically dropped, and physicians became more familiar with the new medication, the amount of patients receiving it skyrocketed. This was particularly true for patients who were bitten by copperheads since Crofab® helped control symptoms and had a much more favorable benefit-to-risk profile than the older antivenom. A retrospective review of envenomations reported to Poison Centers showed a 13.7% national increase in the administration of antivenom for snakebites from 2000-2007. While overall this may only seem like a small increase, the number of patients treated with antivenom after a copperhead envenomation more than tripled, from 9.8% to 35.8%. In Missouri, the number of patients reported to Poison Centers that were treated with antivenom after a snake envenomation increased by 339% from 2000-2007. While I don’t have the exact breakdown, my guess is most of this increase was related to the treatment of copperheads.

Recently, a patient presented to a hospital in California after being bitten by a rattlesnake. From the limited information available, he was treated with antivenom, admitted to an ICU overnight, and discharged the next day. He was charged $128,050 for antivenom alone…more than what I paid for my first house! I bring up this case not to criticize the physician’s decision making or to suggest that the care provided was substandard, because rattlesnake envenomations are associated with cardiovascular dysfunction and coagulopathy, but to make physicians aware of the potential cost of this treatment. To clarify, I’m not advocating withholding Crofab® in all snakebites, or stating that money should be the overriding factor when making patient care decisions, but I do think there are serious financial ramifications for the patient that we need to be aware of when we order this medication. Currently, there are trials underway evaluating Crofab® and its ability to reduce morbidity in copperhead envenomations, such as returning someone to work sooner compared to supportive treatment alone, which may help us in our decision making. However, the results will not be published soon,
and in the meantime, it may be prudent to think twice before ordering Crofab® for the next patient with a mild snakebite that walks through your door.