Lizard Envenomation Medication

Updated: Oct 27, 2015
  • Author: Robert L Norris, MD; Chief Editor: Joe Alcock, MD, MS  more...
  • Print
Medication

Medication Summary

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.

Next:

Cardiovascular Agents

Class Summary

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

Epinephrine (Adrenalin, EpiPen)

Epinephrine is the drug of choice 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.

Previous
Next:

Corticosteroids

Class Summary

Corticosteroids onset of action is approximately 4-6 hours, 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)

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

Prednisone (Deltasone, Orasone, Meticorten)

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

Previous
Next:

Antihistamines

Class Summary

Antihistamines prevent the histamine response in sensory nerve endings and blood vessels. They are more effective in preventing a histamine response than in reversing it.

Diphenhydramine (Benadryl, Benylin, Bydramine)

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

Cimetidine (Tagamet)

Cimetidine is 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 it in addition to H1 antihistamines.

Previous
Next:

Local anesthetics

Class Summary

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

Lidocaine anesthetic

Lidocaine is an amide local anesthetic used in 1-2% concentration. It 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.

Previous
Next:

Analgesics

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)

Fentanyl is a synthetic opioid that is 75-200 times more potent and has a much shorter half-life than morphine sulfate. It 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 the addition of benzodiazepines or other sedatives may result in decreased cardiac output and blood pressure. Fentanyl is highly lipophilic and protein-bound. Prolonged exposure leads to an accumulation in fat and delays the weaning process. Consider using a continuous infusion because of the short half-life of fentanyl. The parenteral form is the drug of choice for conscious sedation analgesia. It is ideal for analgesic action of short duration during anesthesia and the immediate postoperative period. It is an excellent choice for pain management and sedation of short duration (30-60 min), and it is easy to titrate. Its effects are easily and quickly reversed by naloxone.

After initial parenteral dose, subsequent parenteral doses should not be titrated more frequently than every 3 hours or every 6 hours thereafter. Transdermal form is used only for chronic pain conditions in opioid-tolerant patients. When using a transdermal dosage form, the majority of patients are controlled with 72-hour dosing intervals; however, some patients require dosing intervals of 48 hours.

Previous