Question 1

A 13-year-old girl develops persistent sneezing and complains of a scratchy throat. Her grandmother gives the girl a medication from her medicine cabinet. The girl suddenly becomes fatigued and complains of blurry vision and dry mouth. Which of the following is most likely responsible for these symptoms?

A) Loratadine
B) Cetirizine
C) Chlorpheniramine
D) Fexofenadine
E) Azelastine

Chlorpheniramine

Accepted Answer

Chlorpheniramine is a first-generation histamine-1 receptor antagonist, with an increased incidence of central nervous system side effects. The newer agents (such as the other answer choices) have a more polarized molecular structure and do not as easily cross the blood-brain barrier.

Question 2

Which of the following is a physiologic effect of histamine?&#10;A) Decreased bronchiolar smooth muscle tone&#10;B) Decreased systemic vascular resistance&#10;C) Decreased capillary permeability&#10;D) Decreased myocardial contractility&#10;E) Decreased gastric acid secretion

Accepted Answer

Histamine causes vasodilation, leading to decreased systemic vascular resistance. This is part of the body's inflammatory response, increasing blood flow to affected areas.

Question 3

A 10-year-old boy presents to the emergency department in severe shock. His mother states that he was bitten by a wasp before becoming progressively more unresponsive. What is the first medication that should be given to treat the boy's histamine-mediated anaphylaxis?

A) Diphenhydramine
B) Cromolyn sodium
C) Fexofenadine
D) Epinephrine
E) Ranitidine

Epinephrine

Accepted Answer

Epinephrine acts rapidly to reverse anaphylactic symptoms via its stimulation of adrenergic receptors. Alpha-1 effects counteract the drop in systemic vascular resistance. Beta-1 stimulation increases cardiac output to restore perfusion. Beta-2 activation helps to reverse bronchoconstriction. In addition, epinephrine stabilizes mast cells and reduces further histamine release.

Deck 14: Histamine and Antihistamines