Details About Overdose or Poisoning Generic Salt :: Antivenom, Micrurus Fulvius Coral Snake, And Exotic Antivenoms
Antivenom, Micrurus Fulvius (Coral Snake), and Exotic Antivenoms
Drug Pharmacology ::
I. Pharmacology. To produce the antivenom for North American coral snake bites, horses are hyperimmunized with venom from Micrurus fulvius,the eastern coral snake. The lyophilized protein preparation frompooled equine sera contains IgG antibodies to venom fractions as wellas residual serum proteins. Administered intravenously, the antibodiesdistribute widely throughout the body, where they bind the target venom.
Exotic antivenoms. Companiesoutside the United States produce a variety of antivenoms for exoticsnakebites. Most of these products treat snakebites by elapids, sincethis family of snakes causes the most severe envenomations worldwide.The vast majority are still whole-antibody products derived fromhorses. A few are produced as Fab fragments, or the slightly larger Fab2molecule (cleaved with pepsin instead of papain). In both of thesecases, the Fc is removed from the solution. Many foreign antivenomproducts are polyvalent, a mixture of antivenoms for several species.
Drug Indications ::
Indications
Envenomation by the eastern coral snake (M fulvius) or the Texas coral snake (M fulvius tenere).
May not be effective for envenomation by the western, Arizona, or Sonora coral snake (M euryxanthus).
Drug Contra-Indications ::
III. Contraindications. Known hypersensitivity to Micrurus antivenomor to horse serum is a relative contraindication; if a patient withsignificant envenomation needs the antivenom, it should be given withcaution. Antivenoms produced outside of the United States may be madefrom horse or sheep serum.
Drug Adverse Effects ::
IV. Adverse effects
Immediatehypersensitivity, including life-threatening anaphylaxis, may occureven after a negative skin test for horse serum sensitivity.
Delayedhypersensitivity (serum sickness) may occur 1–3 weeks after antivenomadministration, with the incidence and severity depending on the totalquantity of antivenom administered.
C. Use in pregnancy. FDAcategory C (indeterminate). There are no data on teratogenicity.Anaphylactic reactions resulting in shock or hypoxemia in expectantmothers could conceivably affect the fetus adversely. This should beweighed against the potential detrimental effect of the venom on boththe placenta and the fetus (see Table III–1).
D. Exotic antivenoms. All the whole-antibody preparations carry the same risk of immediate and delayed allergy as US-produced whole-IgG antivenoms.
Drug Lab Interactions ::
Drug or laboratory interactions. There are no known interactions.
Drug Dose Management ::
Dosage and method of administration. Generally, the recommended initial dose of Micrurusantivenom is three to five vials. The drug is most effective if givenbefore the onset of signs or symptoms of envenomation. An additionalthree to five vials may be given, depending on the severity ofneurologic manifestations but not on body weight (children may requiredoses as large as or even larger than those for adults).
The recommended dose of exotic snake antivenom will vary. With otherelapids, such as cobras, the antivenom is also more effective if givenearly in the course of the envenomation.
Treat all patients in an intensive care unit setting.
Before a skin test or antivenom administration, insert at least one and preferably two secure intravenous lines.
Performa skin test for horse serum sensitivity, using a 1:10 dilution ofantivenom (some experts prefer this method) or the sample of horseserum provided in the antivenom kit (according to packageinstructions). If the skin test is positive, reconsider the need forantivenom as opposed to supportive care but do not abandon antivenomtherapy if it is needed. Even if the skin test is negative, anaphylaxismay occur unpredictably.
Antivenoms to exotic species may not contain skin-testing solutions. Asmall amount (0.1 mL) of antivenom can be used as a skin test for thesepreparations, or this step may be omitted (especially in the case ofFab and Fab2 antivenoms).
Ifantivenom is used in a patient with a positive skin test, pretreat withintravenous diphenhydramine (see Diphenhydramine) and cimetidine (oranother H2 blocker; Cimetidine and Other H2 Blockers) andhave ready at the bedside a preloaded syringe containing epinephrine(1:10,000 for intravenous use) in case of anaphylaxis. Dilute theantivenom (1:10 to 1:1000) and administer very slowly in these cases.
E. Reconstitute the lyophilized Micrurusantivenom with 10 mL of the diluent supplied, gently swirling for 10–30minutes. Avoid shaking the preparation because this may destroy theimmunoglobulins (as indicated by the formation of foam). Dilution with50–200 mL of saline may aid solubilization.
F. Administer the antivenom intravenously over 15–30 minutes per vial.
G. Exotic elapids.Envenomation by exotic elapids, such as cobras, mambas, and all thepoisonous snakes of Australia, would be expected to produce the same ora worse degree of neurotoxicity as is seen in envenomation from coralsnakes from the United States, and require antivenom administration assoon as possible. It is conceivable that bites from snakes within thesame family could respond to antivenom made from venom of another snakein that family. Therefore, if type-specific antivenom is not availablefor a severe snakebite, same-family antivenom may be substituted withsome possible efficacy. Regional poison centers (1-800-222-1222) may beable to assist in obtaining exotic antivenoms from collectors or zoos.
Drug Chemical Formulations ::
Formulations
Antivenom (M fulvius)vial of lyophilized powder with 0.25% phenol and 0.005% thimerosal aspreservatives. Note that this product is also listed as antivenin (Micrurus fulvius).
Suggested minimum stocking level to treat a 70-kg adult for the first 24 hours is 5–10 vials.
