Moccasin Envenomation Medication
- Author: Sean P Bush, MD, FACEP; Chief Editor: Rick Kulkarni, MD more...
Medication Summary
The physician must be prepared to support the patient's cardiovascular and respiratory systems after any venomous snakebite.
Antivenom
Class Summary
This agent neutralizes toxins from snakebites. Only one antivenom is available: Crotalidae Polyvalent Immune Fab Ovine (CroFab).
Crotaline Fab antivenom (CroFab; Crotaline immune Fab (ovine), Protherics, Nashville, TN) is a highly purified product derived from sheep hyperimmunized with the venom of 4 crotaline snakes, including Agkistrodon piscivorus. A relatively pure IgG fraction is extracted from the sheep serum and cleaved with papain to remove the antigenic Fc portion. Column affinity purification is then used to produce product consisting almost entirely of Fab fragments with specific affinity to snake venom.[15]
Antivenoms can be associated with acute and delayed allergic reactions. However, both the incidence and the severity of these reactions are low with crotaline Fab antivenom.
Urticaria has been reported in approximately 8% of patients treated with crotaline Fab antivenom; wheezing is reported in 2% and serum sickness in less than 10%. No deaths have been reported, and almost all patients have been able to complete antivenom therapy after treatment of mild allergic reactions.
Improved safety compared to historically utilized antivenoms has lead to a change in the management of moccasin envenomation.[16] However, the cost of therapy is significant, and cost-benefit analysis is not available.[17]
Significant clinical experience, including published case series, supports the role of Crotaline Fab antivenom in severe envenomations.[18]
Crotaline Fab antivenom has been formally tested in humans envenomated by cottonmouth snakes (Agkistrodon piscivorus), but not in humans envenomated by copperheads (A contortrix). However, a large retrospective case series supports the effectiveness of Fab antivenom in treatment of copperhead bites.
Another antivenom (Anavip, manufactured by Instituto Bioclon) has been FDA approved for experimental use and is currently undergoing phase III clinical trials.
CroFab (Crotalidae Polyvalent Immune Fab Ovine)
Appears to be more specific against moccasin venom and less allergenic than Antivenin (Crotalidae) Polyvalent.
Crotalidae polyvalent antivenom (equine)
Because moccasin envenomations are usually milder than those inflicted by rattlesnakes and because of the potentially severe adverse reactions associated with this product, use is generally contraindicated except as last resort.
Immunizations
Class Summary
Immunize patients against tetanus.
Diphtheria-tetanus toxoid (dT)
Used to induce active immunity against tetanus in selected patients. Tetanus and diphtheria toxoids are the immunizing agents of choice for most adults and children >7 y. Booster doses are necessary to maintain tetanus immunity throughout life because tetanus spores are ubiquitous.
Pregnant patients should receive only tetanus toxoid, not a diphtheria antigen–containing product. In children and adults, immunization may be administered into the deltoid or midlateral thigh muscles. In infants, the preferred site of administration is the mid thigh laterally.
Hematologic agents
Class Summary
Consider transfusion, in conjunction with ongoing antivenom administration, if antivenom alone does not correct severe coagulopathy or patient has active severe bleeding. Transfusion is generally recommended for life-threatening bleeding (rare), platelets < 20,000 mm3, or hemoglobin < 7 g/dL. Use transfusion as temporizing measure only after adequate antivenom therapy because antivenom may correct coagulopathies more definitively. Coagulopathy often recurs and may persist for as long as 2 weeks after envenomation.
Platelets, fresh frozen plasma (FFP), and packed RBCs (PRBCs)
These agents are preferred initially to whole blood because they limit volume, immune, and storage complications. PRBCs have 80% less plasma, are less immunogenic, and can be stored about 40 d (vs 35 d for whole blood). PRBCs are obtained after centrifugation of whole blood. Leukocyte-poor PRBCs are used in patients who are transplant candidates/recipients or in those with prior febrile transfusion reactions. Washed or frozen PRBCs are used in individuals with hypersensitivity transfusion reactions.
Wingert WA, Pattabhiraman TR, Cleland R, Meyer P, Pattabhiraman R, Russell FE. Distribution and pathology of copperhead (agkistrodon contortrix) venom. Toxicon. 1980;18(5-6):591-601. [Medline].
Sullivan JB, Wingert WA, Norris RL Jr. North American venomous reptile bites. In: PS Auerbach, ed. Wilderness Medicine: Management of Wilderness and Environmental Emergencies. Vol 2. St. Louis: Mosby-Year Book; 1995:680-709.
Thorson A, Lavonas EJ, Rouse AM, Kerns WP 2nd. Copperhead envenomations in the Carolinas. J Toxicol Clin Toxicol. 2003;41(1):29-35. [Medline].
Bronstein AC, Spyker DA, Cantilena LR Jr, Green J, Rumack BH, Heard SE. 2006 Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS). Clin Toxicol (Phila). Dec 2007;45(8):815-917. [Medline].
Spiller HA, Bosse GM. Prospective study of morbidity associated with snakebite envenomation. J Toxicol Clin Toxicol. 2003;41(2):125-30. [Medline].
Bush SP, Thomas TL, et al. Envenomations in children. Pediatr Emerg Med Rep. 1997;2:1-12.
Scharman EJ, Noffsinger VD. Copperhead snakebites: clinical severity of local effects. Ann Emerg Med. Jul 2001;38(1):55-61. [Medline].
Bush SP, Hegewald KG, Green SM, Cardwell MD, Hayes WK. Effects of a negative pressure venom extraction device (Extractor) on local tissue injury after artificial rattlesnake envenomation in a porcine model. Wilderness Environ Med. Fall 2000;11(3):180-8. [Medline].
Bush SP. Snakebite suction devices don't remove venom: they just suck. Ann Emerg Med. Feb 2004;43(2):187-8. [Medline].
Burch JM, Agarwal R, Mattox KL, Feliciano DV, Jordan GL Jr. The treatment of crotalid envenomation without antivenin. J Trauma. Jan 1988;28(1):35-43. [Medline].
Whitley RE. Conservative treatment of copperhead snakebites without antivenin. J Trauma. Aug 1996;41(2):219-21. [Medline].
Dart RC, McNally JT, Spaite DW, Gustafson R. The Sequelae of Pitviper Poisoning in the United States. In: Campbell JA, Brooks DE, editors. Biology of the Pitvipers: Tyler, TX: Selva; 2002:395-404.
Gold BS, Wingert WA. Snake venom poisoning in the United States: a review of therapeutic practice. South Med J. Jun 1994;87(6):579-89. [Medline].
Lavonas EJ, Ruha AM, Banner W, Bebarta V, Bernstein JN, Bush SP, et al. Unified treatment algorithm for the management of crotaline snakebite in the United States: results of an evidence-informed consensus workshop. BMC Emerg Med. Feb 3 2011;11:2. [Medline]. [Full Text].
Dart RC, Seifert SA, Carroll L, Clark RF, Hall E, Boyer-Hassen LV, et al. Affinity-purified, mixed monospecific crotalid antivenom ovine Fab for the treatment of crotalid venom poisoning. Ann Emerg Med. Jul 1997;30(1):33-9. [Medline].
Lawrence WT, Giannopoulos A, Hansen A. Pit viper bites: rational management in locales in which copperheads and cottonmouths predominate. Ann Plast Surg. Mar 1996;36(3):276-85. [Medline].
Ruha AM, Curry SC, Beuhler M, Katz K, Brooks DE, Graeme KA, et al. Initial postmarketing experience with crotalidae polyvalent immune Fab for treatment of rattlesnake envenomation. Ann Emerg Med. Jun 2002;39(6):609-15. [Medline].
Dart RC, Seifert SA, Boyer LV, Clark RF, Hall E, McKinney P, et al. A randomized multicenter trial of crotalinae polyvalent immune Fab (ovine) antivenom for the treatment for crotaline snakebite in the United States. Arch Intern Med. Sep 10 2001;161(16):2030-6. [Medline].
Jurkovich GJ, Luterman A, McCullar K, et al. Complications of Crotalidae Antivenin Therapy. Journal of Trauma. 1998;28:1032-1037.
Lavonas EJ, Gerardo CJ, O'Malley G, Arnold TC, Bush SP, Banner W Jr, et al. Initial experience with Crotalidae polyvalent immune Fab (ovine) antivenom in the treatment of copperhead snakebite. Ann Emerg Med. Feb 2004;43(2):200-6. [Medline].
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