Medication Summary
Medication use varies depending on the severity of the wasp sting.
Antihistamines are used to treat mild urticarial symptoms. In a Canadian study, the use of an antihistamine reduced the progression to anaphylaxis from 3.4% without the H1 blocker to 1.9% with the H1 blocker. [33, 35] H2 blockers were more effective in decreasing urticaria from 46% to 14%. [35]
Catecholamines are needed in extreme cases (eg, anaphylaxis).
Antihistamines
Class Summary
H1-receptor antagonists block the effects of histamine. Diphenhydramine and hydroxyzine are two of the most widely used H1 blockers for oral and parenteral use in wasp stings.
Diphenhydramine (Benadryl, Aler-Dryl, Altaryl, Banophen, Diphen, Geri-Dryl)
Diphenhydramine is used for symptomatic relief of symptoms caused by release of histamine in allergic reactions.
Hydroxyzine (Vistaril)
Hydroxyzine antagonizes H1 receptors in the periphery and may suppress histamine activity in the subcortical region of the CNS.
Corticosteroids
Class Summary
These agents modulate and decrease the inflammatory response to the sting. Onset of action is delayed for several hours; therefore, glucocorticoids have very little effect in the acute setting. Early administration continues to stabilize the patient.
Methylprednisolone (Solu-Medrol, Medrol, A-Methapred, Depo-Medrol)
Steroids ameliorate the delayed effects of anaphylactoid reactions and may limit biphasic anaphylaxis. In severe cases of serum sickness, parenteral steroids may be beneficial to reduce the inflammatory effects of this immune complex–mediated disease.
Prednisone (Deltasone, Rayos)
Prednisone may decrease inflammation by reversing increased capillary permeability and suppressing PMN activity.
Sympathomimetics
Class Summary
Epinephrine and the inhaled beta agonist albuterol reverse the effect of histamine (rather than blocking the effect).
Epinephrine (Adrenalin, EpiPen)
Epinephrine is the drug of choice for treating anaphylactoid reactions. It has alpha-agonist effects that include increased peripheral vascular resistance, reversed peripheral vasodilatation, systemic hypotension, and vascular permeability. Beta-agonist effects of epinephrine include bronchodilatation, chronotropic cardiac activity, and positive inotropic effects.
Epinephrine can be administered subcutaneously for mild-to-moderate reactions and intravenously and via an endotracheal tube.
Albuterol (Proventil HFA, Ventolin HFA, ProAir HFA, Vospire ER, AccuNeb)
Albuterol is a beta-agonist for bronchospasm refractory to epinephrine. It relaxes bronchial smooth muscle by action on beta2 receptors, with little effect on cardiac muscle contractility.
Histamine H2 Antagonists
Class Summary
The combination of H1 and H2 antagonists may be useful in chronic idiopathic urticaria not responding to H1 antagonists alone. It may also be useful for itching and flushing in anaphylaxis, pruritus, urticaria, and contact dermatitis.
Famotidine (Pepcid, Acid Reducer, Heartburn Relief)
Famotidine is an H2 antagonist that, when combined with an H1 type, may be useful in treating allergic reactions that do not respond to H1 antagonists alone.
Cimetidine (Tagamet HB, Cimetidine Acid Reducer)
Cimetidine is an H2 antagonist that, when combined with an H1 type, may be useful in treating allergic reactions that do not respond to H1 antagonists alone.
Ranitidine (Zantac, Zantac 150 Maximum Strength, Zantac 75, Deprizine RapidPaq)
Ranitidine is a competitive, reversible inhibitor of histamine at the H2 receptor that may be used in conjunction with H1-blockers for severely symptomatic cases. It has fewer drug interactions than cimetidine and may be better for patients who take other medications metabolized by the cytochrome p450 system.
Vasopressors
Class Summary
Vasoconstrictors reduce portal blood flow and/or increase resistance to variceal blood flow inside the varices. Therefore, these drugs reduce blood flow in the gastroesophageal collaterals because of their vasoactive effects on the splanchnic vascular system. In general, this class of drugs provides hemodynamic support.
Vasopressin (Vasostrict)
Vasopressin has vasopressor and antidiuretic hormone (ADH) activity. It increases water resorption at the distal renal tubular epithelium (ADH effect) and promotes smooth muscle contraction throughout the vascular bed of the renal tubular epithelium (vasopressor effects). However, vasoconstriction is also increased in splanchnic, portal, coronary, cerebral, peripheral, pulmonary, and intrahepatic vessels. Vasopressin decreases portal pressure in portal hypertension.
Alpha/Beta Adrenergic Agonists
Class Summary
Cardiovascular performance deteriorates and cardiac output falls if effective therapy is not administered. Adrenergic antagonists improve the patient’s hemodynamic status by increasing myocardial contractility and heart rate, resulting in increased cardiac output. They also increase peripheral resistance by causing vasoconstriction. Increased cardiac output and increased peripheral resistance lead to increased blood pressure.
Norepinephrine (Levophed)
Norepinephrine is used in protracted hypotension after adequate fluid replacement. It stimulates beta1- and alpha-adrenergic receptors, which in turn increases cardiac muscle contractility and heart rate, as well as vasoconstriction. As a result, it increases systemic blood pressure and cardiac output. Adjust and maintain infusion to stabilize blood pressure (eg, 80-100 mm Hg systolic) sufficiently to perfuse vital organs.
Glucose-Elevating Agents
Class Summary
Glucagon uses a different receptor than that used by sympathomimetics to stimulate intracellular cAMP production, increasing cardiac conduction and contractility. Glucagon has positive inotropic and chronotropic effects, which may be useful for treating bradycardia caused by calcium channel blockers.
Glucagon (Glucagon Emergency)
Glucagon is the drug of choice for severe anaphylaxis in patients who take beta-blockers (should be used in addition to epinephrine, not as a substitute).
Pancreatic alpha cells of the islets of Langerhans produce glucagon, a polypeptide hormone. It exerts opposite effects of insulin on blood glucose. Glucagon elevates blood glucose levels by inhibiting glycogen synthesis and enhancing formation of glucose from noncarbohydrate sources, such as proteins and fats (gluconeogenesis). It increases the hydrolysis of glycogen to glucose (glycogenolysis) in the liver in addition to accelerating hepatic glycogenolysis and lipolysis in adipose tissue. Glucagon also increases the force of contractions in the heart and has a relaxant effect on the GI tract.
The dose used for anaphylaxis is higher than the usual dose of 1 mg (1 U) IV/IM/SC used to treat hypoglycemia.
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Western paper wasp (Mischocyttarus flavitarsis) building a nest. By Sanjay Acharya (self-made at Sunnyvale, California, USA). Courtesy of Wikimedia Commons.
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Yellow jacket. By Richard Bartz, Munich aka Makro Freak (Own work). Courtesy of Wikimedia Commons.
