(an-tie-ven-nin) North American Coral Snake Antivenin
ANTIDOTE
Note:The location of antivenins for rare species and the telephone numbers for envenomation experts are available from the Arizona Poison and Drug Information Center (800-222-1222). The National Animal Poison Control Center (888-426-4435) is another source for up-to-date snakebite treatment recommendations.
This product is indicated for the treatment of envenomation from the Eastern coral snake (Micrurus fulvius fulvius) and the Texas coral snake (Micrurus fulvius tenere). It will not neutralize the venom form the Sonoran or Arizona coral snake (Micruroides euryxanthus) or the Brazilian giant coral snake (Micrurus frontalis). Coral snake envenomation is quite rare in the United States and approximately 60% of coral snake bites do not result in envenomation. Unlike pit viper venom, coral snake venom primarily causes neurotoxicity and clinical signs may be delayed. It has been recommended that animals suspected of a coral snake envenomation be hospitalized with close observation for 24–48 hours post-bite.
Antivenins act by neutralizing the venoms (complex proteins) in patients via passive immunization of globulins obtained from horses immunized with the venom. Each vial of antivenin will neutralize approximately 2 mg of M. fulvius fulvius venom.
The coral snake antivenin will not neutralize M. euryxanthus (Sonoran or Arizona Coral Snake) venom. Because there is a risk of anaphylaxis occurring secondary to the horse serum, many recommend performing sensitivity testing before administration.
The most significant adverse effect associated with the use of these products is anaphylaxis secondary to the equine serum source of this product. An incidence rate of less than 2% has been reported. A 1:10 dilution of the antivenin given intracutaneously at a dose of 0.02–0.03 mL may be useful as a test for hypersensitivity. Wheal formation and erythema indicate a positive reaction and are generally seen within 30 minutes of administration. A negative response does not insure that anaphylaxis will not occur, however. A pretreatment dose of diphenhydramine is often recommended before administering antivenin. Should an anaphylactoid reaction be detected, stopping the infusion, giving an additional dose of diphenhydramine and restarting the infusion 5 minutes later at a slower rate may allow the dose to be administered without further problems.
In humans, the FDA categorizes this drug as category C for use during pregnancy (Animal studies have shown an adverse effect on the fetus, but there are no adequate studies in humans; or there are no animal reproduction studies and no adequate studies in humans).
The following drug interactions have either been reported or are theoretical in humans or animals receiving antivenin and may be of significance in veterinary patients:
Note: The treatment of Coral snakebite involves significant treatment and monitoring beyond administration of antivenin. It is highly recommended to refer to specialized references e.g., (Peterson 2006a) or to contact an animal poison control center for guidance beyond what is listed below.
Coral Snake antivenin (not Sonoran or Arizona variety):
a) Dogs: After testing for hypersensitivity give 1–2 vials initially, and more in 4–6 hours if necessary. Therapy is best started within 4 hours after envenomation. Supportive care includes broad-spectrum antibiotics, fluid therapy and mechanical ventilation if necessary. Corticosteroids are not recommended. (Marks, Mannella et al. 1990)
b) Dogs/Cats: Dose necessary is calculated relative to the amount of venom injected and the body mass of patient. Average dose required for dogs or cats is 1–2 vials of antivenin. The earlier the antivenin is administered the more effective it is. Smaller patients may require higher doses (as venom amount/kg body weight is higher), and multiple vials may be necessary. Initially give one vial, by diluting to 100–250 mL of crystalloid fluids and initially administering by slow IV. In smaller patients, adjust infusion volume to prevent fluid overload. Give additional vials as indicated by the progression of the syndrome. (Peterson 2006b)
Coral Snake Antivenin:
a) Use only if necessary to treat systemic effects, otherwise avoid use. Administer 1–2 vials slowly IV diluted in 250–500 mL saline or lactated Ringer’s. Administer antihistamines; corticosteroids are contraindicated. May be used with Crotilidae antivenin. (Bailey and Garland 1992)
Clients must be made aware of the potential for anaphylaxis as well as the expenses associated with treatment, monitoring and hospitalization.
These products are concentrated serum globulins obtained from horses immunized with the venoms of several types of snakes. They are provided as refined, lyophilized product with a suitable diluent.
Product should be stored in the refrigerator. Avoid freezing and excessive heat. Reconstitute vial with 10 mL of the supplied diluent. Gentle agitation may be used to hasten dissolution of the lyophilized powder. Reconstituted vials should be used within 48 hours (keep refrigerated) and within 12 hours once added to IV solutions.
Note: The availability status of antivenins in the USA is in flux. It is highly recommended to contact a poison control center (see sample phone numbers at the top of this monograph) to get current recommendations on availability and treatment options.
VETERINARY-LABELED PRODUCTS: None
HUMAN-LABELED PRODUCTS:
Antivenin (Micrurus fulvius) Powder for Injection lyophilized: in single-use vials with 1 vial diluent (10 mL water for injection); Antivenin (Micrurus fulvius); (Ayerst); (Rx). Note: The manufacturer has discontinued producing this product, but has enough antivenin on hand to satisfy demand for several years.