Lizard Envenomation Medication

No specific agents are used to treat lizard envenomations. Although 2 experimental antivenoms have been produced for the Gila monster, neither has been made commercially available. Drug therapy is entirely symptomatic (eg, local anesthetics, analgesics, antiemetics). If antibiotics are administered, they should be broad-spectrum and they should provide coverage for gram-negative organisms. For the rare case of anaphylaxis/angioedema, therapy should be instituted with sympathomimetic agents, antihistamines, and/or steroids.

Class Summary

Possess alpha- and beta-adrenergic effects that are useful in reversing anaphylactic reactions (eg, angioedema, bronchospasm, hypotension).

Epinephrine (Adrenalin, EpiPen)

DOC for the treatment of anaphylactoid reactions. Alpha-agonist effects increase peripheral vascular resistance and reverse peripheral vasodilatation and vascular permeability, thus helping to restore vascular tone and blood pressure. The beta-agonist effects increase heart rate and inotropism and cause bronchodilatation

Class Summary

Onset of action is approximately 4-6 h, although some synergistic activity may be noted when simultaneously used with sympathomimetic agents. Steroids may be needed in the rare event of an allergic reaction to lizard venom. Corticosteroids have no role in the management of envenomation itself.

Methylprednisolone (Solu-Medrol)

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

Prednisone (Deltasone, Orasone, Meticorten)

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

Class Summary

Prevent the histamine response in sensory nerve endings and blood vessels. More effective in preventing histamine response than in reversing it.

Diphenhydramine (Benadryl, Benylin, Bydramine)

Used for the symptomatic relief of allergic symptoms caused by histamine released in response to allergens.

Cimetidine (Tagamet)

An 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-receptor antagonists alone. Use in addition to H1 antihistamines.

Class Summary

Local anesthetics can be injected, either locally or regionally, to aid in exploration of wounds (to rule out damage to underlying structures or retained teeth).

Lidocaine anesthetic

Amide local anesthetic used in 1-2% concentration. Inhibits depolarization of type C sensory neurons by blocking sodium channels. Epinephrine should be avoided in venomous lizard bites to prevent causing additional local tissue ischemia.

Class Summary

Patients may require narcotic analgesics for pain control after venomous lizard bites. In choosing a narcotic analgesic, to prevent worsening venom effects, it is best to select a narcotic that has less tendency to induce histamine release, such as fentanyl.

Fentanyl citrate (Sublimaze)

A synthetic opioid that is 75-200 times more potent and much shorter half-life than morphine sulfate. Has less hypotensive effects and is safer in patients with hyperactive airway disease than morphine because of minimal-to-no associated histamine release. By itself, it causes little cardiovascular compromise, although addition of benzodiazepines or other sedatives may result in decreased cardiac output and blood pressure.

Highly lipophilic and protein-bound. Prolonged exposure leads to accumulation in fat and delays weaning process.

Consider continuous infusion because of the short half-life of fentanyl. Parenteral form is DOC for conscious sedation analgesia. Ideal for analgesic action of short duration during anesthesia and immediate postoperative period.

Excellent choice for pain management and sedation with short duration (30-60 min) and easy to titrate. Easily and quickly reversed by naloxone.

After initial parenteral dose, subsequent parenteral doses should not be titrated more frequently than q3h or q6h thereafter.

Transdermal form is used only for chronic pain conditions in opioid-tolerant patients. When using transdermal dosage form, majority of patients are controlled with 72-h dosing intervals; however, some patients require dosing intervals of 48 h.

Easily and quickly reversed by naloxone.