Question 1

Which of the following best describes the mechanism of action of antihistamines?

Accepted Answer

They antagonize the action of histamine at its receptor sites.

Question 2

A patient develops urticaria and pruritus after receiving a blood transfusion. Which type of hypersensitivity reaction is most likely responsible?

Accepted Answer

Type II (antibody-mediated cytotoxic reaction)

Question 3

Which of the following statements about histamine is correct?

Accepted Answer

Histamine is synthesized and stored in most body tissues, especially those exposed to the environment.

Question 4

A 7-year-old child with a history of seasonal allergies is prescribed cetirizine. Which property of cetirizine makes it preferable over diphenhydramine for this patient?

Accepted Answer

Cetirizine does not readily enter the brain, reducing sedation.

Question 5

Which of the following clinical manifestations is most likely to result from a type IV hypersensitivity reaction?

Accepted Answer

Contact dermatitis from poison ivy

Question 6

A patient presents with watery nasal drainage, sneezing, and itching of the eyes during spring. Which type of hypersensitivity reaction is responsible for these symptoms?

Accepted Answer

Type I (immediate hypersensitivity)

Question 7

Which of the following is a distinguishing feature of third-generation H1 receptor antagonists such as fexofenadine?

Accepted Answer

They bind preferentially to peripheral H1 receptors, reducing drowsiness.

Question 8

A patient experiences an anaphylactoid reaction after receiving a medication for the first time. Which of the following best explains this phenomenon?

Accepted Answer

It is a pseudoallergic reaction that mimics anaphylaxis but does not involve antibodies or sensitized T lymphocytes.

Question 9

Which of the following best describes the role of antihistamines in the management of hypersensitivity reactions?

Accepted Answer

They relieve symptoms but do not address the underlying hypersensitivity.

Question 10

A patient with chronic kidney disease is prescribed an antihistamine. Which of the following is the most important consideration for this patient?

Accepted Answer

Dose adjustment may be necessary due to altered pharmacokinetics.

Question 11

Which of the following foods is most likely to trigger an anaphylactic reaction in a child with a known food allergy?

Accepted Answer

Peanut

Question 12

Which of the following is a common adverse effect associated with first-generation H1 receptor antagonists?

Accepted Answer

Drowsiness and anticholinergic effects

Question 13

A patient develops serum sickness after receiving antitoxin therapy. Which type of hypersensitivity reaction is this?

Accepted Answer

Type III

Question 14

Which of the following best explains why second- and third-generation antihistamines are preferred for treating allergic rhinitis in adults who need to remain alert?

Accepted Answer

They do not readily cross the blood-brain barrier, reducing drowsiness.

Question 15

Which of the following is a correct pairing of hypersensitivity type and example?

Accepted Answer

Type II – Hemolytic anemia

Question 16

A patient with a history of allergic rhinitis is prescribed fexofenadine. Which property of this drug is most beneficial for this patient?

Accepted Answer

It binds preferentially to peripheral H1 receptors, minimizing central nervous system side effects.

Question 17

Which of the following is NOT a typical indication for antihistamine use?

Accepted Answer

Bacterial pneumonia

Question 18

A patient develops a rash after direct contact with latex gloves. Which immune mechanism is most likely responsible?

Accepted Answer

Antigen-specific T cell-mediated delayed hypersensitivity

Question 19

Which of the following best describes the pharmacologic action of H1 receptor antagonists on the respiratory tract?

Accepted Answer

They inhibit smooth muscle constriction, reducing symptoms such as bronchospasm.

Question 20

A patient with a history of severe allergic reactions is being educated about antihistamine therapy. Which statement by the patient indicates a need for further teaching?

Accepted Answer

"Antihistamines will prevent me from ever having another allergic reaction."

Chapter 32: Drug Therapy to Decrease Histamine Effects and Allergic Response

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