Brown Snake Envenomation Medication

The antidote for systemic envenomations by the brown snake is the equine-derived antivenin. In a study of 35 patients with severe brown snake envenomation, two thirds of the cases were neutralized with 5 ampules and 89% were neutralized with 10 ampules.^[2] As with all equine-derived antivenins, anaphylaxis should be anticipated and treated if any allergic reactions occur. Pretreatment with antihistamines and corticosteroids should be included.

Hypotension should be treated with isotonic crystalloid infusions and vasopressors if blood pressure is refractory to fluids alone.

Tetanus toxoid should be given when indicated.

Cholinesterase inhibitors, such as edrophonium and neostigmine, may be given to palliate the neurological sequelae of the venom but should not replace definitive airway control.

Class Summary

Gives passive immunity to the venom and should be administered immediately if any signs of systemic toxicity are present.

Antivenin

According to the Antivenin Index, the monovalent form is not carried in the US but may be found in Australia (Commonwealth Serum Laboratories, Melbourne, Australia). The polyvalent antivenin may be obtained at the Bronx Zoo, but a local zoo may be contacted.

Skin testing before antivenin administration is not recommended because it may sensitize the individual to future antivenin use and will delay the administration of the antivenin. Antihistamines and subcutaneous epinephrine should be administered (if no contraindications are present) before giving the antivenin.

1 U neutralizes 0.01 mg venom in vitro.

Class Summary

H1 and H2 blockers should be given to prevent immune mediated responses and may be continued for an additional 5 days or for as long as symptoms persist.

Diphenhydramine (Benadryl)

For symptomatic relief of symptoms caused by release of histamine in allergic reactions.

Cimetidine (Tagamet)

H2 antagonist that, when combined with an H1 type, may be useful in treating itching and flushing in anaphylaxis, pruritus, urticaria, and contact dermatitis that do not respond to H1 antagonists alone. Use this medication in addition to H1 antihistamines.

Chlorpheniramine (Chlor-Trimeton)

Competes with histamine or H1-receptor sites on effector cells in blood vessels and respiratory tract.

Class Summary

Should be employed when evidence of an allergy-mediated event is present. However, onset of action is approximately 4-6 h and has limited benefit in the initial acute treatment of the rapidly deteriorating anaphylactic patient. Nonetheless, corticosteroids may benefit patients with persistent bronchospasm or hypotension.

Methylprednisolone (Solu-Medrol)

Decreases inflammation by suppressing the migration of polymorphonuclear leukocytes and reversing increased capillary permeability.

Prednisone (Deltasone, Orasone, Sterapred)

Used for the treatment of a variety of diseases including serum sickness in the outpatient setting. Prednisone is inactive and must be metabolized to the active metabolite prednisolone. The conversion may be impaired in patients with liver disease.

Class Summary

These agents have combined alpha- and beta-adrenergic agonist action and are the agents of first choice in the treatment of anaphylaxis.

An additional option in the management of persistent bronchospasm may be anticholinergic agents. These agents block the action of acetylcholine at parasympathetic sites in bronchial smooth muscle.

Epinephrine (Adrenalin, EpiPen)

DOC for treating anaphylactoid reactions. The alpha-agonist effects of epinephrine increase peripheral vascular resistance and reverse peripheral vasodilatation, vascular permeability, and systemic hypotension. Conversely, the beta-agonist effects produce bronchodilatation, positive inotropic and chronotropic cardiac activity, and result in an increased production of intracellular cAMP.

Albuterol (Ventolin, Proventil)

Beta-agonist useful in the treatment of bronchospasm that is refractory to epinephrine. Relaxes bronchial smooth muscle by action on beta 2-receptors and has little effect on cardiac muscle contractility

Theophylline (Aminophylline, Theo-Dur, Slo-bid)

Potentiates exogenous catecholamines. Stimulates endogenous catecholamine release and diaphragmatic muscular relaxation, which in turn stimulates bronchodilation.

For bronchodilation, near toxic (>20 mg/dL) levels are usually required.

Ipratropium (Atrovent)

Chemically related to atropine. Has antisecretory properties and, when applied locally, inhibits secretions from serous and seromucous glands lining the nasal mucosa.

Class Summary

May be useful in reversing neurological complications of the venom; however, they should not be a substitute for airway management.

Edrophonium (Enlon, Reversol, Tensilon)

Short active cholinesterase inhibitor that inhibits the destruction of acetylcholine by acetylcholinesterase and may palliate weakness. Facilitates transmission of impulses across myoneural junction and results in increased cholinergic responses (eg, miosis, increased tonus of intestinal and skeletal muscles, bronchial and ureteral constriction, bradycardia, and increased salivary and sweat gland secretions).

Usually administered IV, but, if this is not possible, IM/SC route may be used.

Neostigmine (Prostigmin)

Longer acting cholinesterase inhibitor that can be used when edrophonium is ineffective. Inhibits destruction of acetylcholine by acetylcholinesterase, which facilitates transmission of impulses across myoneural junction.

Class Summary

Consists of administration of immunoglobulin pooled from serum of immunized subjects.

Tetanus immune globulin (TIG)

Used for passive immunization of any person with a wound that might be contaminated with tetanus spores.