Coral Snake Envenomation Medication
- Author: Robert L Norris, MD; Chief Editor: Joe Alcock, MD, MS more...
Definitive therapy for coral snake envenomation is antivenom administration. Antivenom (usually derived from horses or sheep) is generally specific for closely related species of snakes, and no advantage exists to giving antivenom developed for unrelated snakes. Administering antivenom made from the venoms of unrelated snakes may add complications of acute or delayed adverse reactions (eg, nonallergic anaphylaxis [anaphylactoid reaction], delayed serum sickness) to an already serious situation. If specific antivenom is unavailable, compression and immobilization should be maintained and the airway and respiratory status supported as necessary. An appropriately applied compression/immobilization device should be removed only after supportive measures are in place and antivenom, if available, is obtained.
In the United States, the product used to treat Micrurus bites for the last several decades, Wyeth's North American Coral Snake (Micrurus fulvius) Antivenin, is no longer in production and current stock is due to expire in April 2016. Other antivenoms are produced in other countries (eg, Brazil, Costa Rica) for non-North American coral snakes. Mexico produces an antivenom that is likely effective for coral snake bites in the United States. One of these foreign antivenoms may prove useful for treatment of coral snake bites in the United States, and research in this area continues. Assistance in locating and securing an appropriate antivenom can be obtained by contacting a regional poison control center.
In the absence of such an antivenom, care will be entirely supportive.
Care for persons bitten by Sonoran coral snakes is entirely supportive because no specific antivenom is available for this species.
Any appropriate, available antivenom should be administered according to the manufacturer's instructions.
As with any form of bite, tetanus status should be updated as necessary.
Antibiotic prophylaxis is not indicated. Because of the relative paucity of enzymatic necrotic components in their venoms, coral snake bites tend to cause little local tissue damage, and secondary infections are rare.
These agenst impart passive immunity to the patient against the venom components of the snake(s) for which it is manufactured. The heterologous antibodies administered bind with venom antigens and block their deleterious effects.
This historically is the drug of choice for significant bites by M fulvius (eastern coral snake) and M tener (Texas coral snake); however, it is no longer being produced. Unless another known effective antivenom is available, care for victims bitten by coral snakes in the United States will have to rely entirely on supportive care (as per the text above), though the outcome should still be good.
H1 and H2 blockers may blunt or prevent acute allergic reaction when given before the administration of antivenom. If an anaphylactoid reaction occurs despite pretreatment, further antihistamine dosing may be required. They are also useful in managing pruritus in cases of delayed serum sickness, which may appear days to weeks following antivenom treatment.
Diphenhydramine is administered parenterally and often is the H1 blocker of choice in treating or preventing anaphylactic/anaphylactoid reactions. It is also effective in oral forms for treating itching associated with serum sickness.
Cimetidine is administered parenterally and often is the H2 blocker of choice in treating or preventing anaphylactoid reactions. Use this medication in addition to H1 antihistamines.
These agents are useful in treating acute allergic reactions that may occur with antivenom administration and in supporting the blood pressure and tissue perfusion of hypotensive patients with shock unresponsive to IV fluids and antivenom.
Epinephrine is the drug of choice for treating anaphylactoid reactions. It has alpha-agonist effects that increase peripheral vascular resistance and reverse peripheral vasodilatation, systemic hypotension, and vascular permeability. Conversely, the beta-agonist activity of epinephrine produces bronchodilatation, chronotropic cardiac activity, and positive inotropic effects.
Dopamine may be required to support blood pressure with hypotension caused by an anaphylactoid reaction that is unresponsive to fluids and epinephrine or by direct coral snake venom effects that are unresponsive to fluids and antivenom.
Norepinephrine may be used as an alternative to dopamine to support blood pressure in the face of hypotension caused by an anaphylactoid reaction that is unresponsive to fluids and epinephrine.
Corticosteroids are essential for the management of acute and delayed allergic phenomena following antivenom administration. Steroids have no primary role in the management of snake envenomation.
Methylprednisolone ameliorates the delayed effects of anaphylactoid reactions and may limit biphasic anaphylaxis. In severe cases of serum sickness, parenteral steroids may reduce the inflammatory effects of this immune-complex mediated disease.
This or other oral forms of corticosteroids (eg, prednisolone) are useful in managing mild-to-moderate serum sickness on an outpatient basis.
Immune globulins bind toxoids, stimulate an immune response, and offer transient protection while the host immune system develops antibodies.
Tetanus immune globulin is used for passive immunization if the wound might be contaminated with tetanus spores when the patient has no history of completing a primary tetanus immunization series.
This is used to induce active immunity against tetanus.
The immunizing agent of choice for most adults and children older than 7 years is tetanus and diphtheria toxoids. It is necessary to administer booster doses to maintain tetanus immunity throughout life. Pregnant patients should receive only tetanus toxoid, not a diphtheria antigen-containing product. In children and adults, it may be administered into the deltoid or midlateral thigh muscles. In infants, the preferred site of administration is the mid thigh laterally.
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