Question 1

What type of antibody is produced the first time a person is sensitized by tree pollen?

Accepted Answer

The first time a person comes into contact with tree pollen, dust mites, or other allergens (antigens), white blood cells produce antibodies, specifically IgE immunoglobulins.

Question 2

Nonselective interactions of first-generation antihistamines include:

Accepted Answer

These characteristically have a nonselective interaction with peripheral and central (CNS) histamine receptors. These drugs can be used interchangeably and frequently cause sedation (CNS) along with relief of allergy symptoms.

Question 3

What role do H₁-receptors play in the bronchioles for patients with asthma?

Accepted Answer

Contraction of the bronchiolar smooth muscle results in bronchoconstriction, which makes breathing difficult.

Question 4

What occurs in an allergic reaction when histamine binds to receptors on sensory nerve endings?

Accepted Answer

Itching and pain occur because histamine binds to receptors on local sensory nerve endings and causes itch-specific fibers to send information to the spinal cord and brain (spinothalamic tract).

Question 5

Eczematoid dermatitis can occur with antihistamines as a result of:

Accepted Answer

The prolonged indiscriminate use of topical antihistaminic preparations can lead to the development of hypersensitivity in some people. This hypersensitivity may range from rashes to eczematoid dermatitis, in which lesions on the skin surface ooze and develop scaly crusts.

Question 6

Advantages of newer-generation antihistaminics over first-generation antihistaminics are:

Accepted Answer

These agents are not as sedating or drying and demonstrate equal antiallergic activity to the first-generation drugs.

Question 7

Why do first-generation antihistaminics require repeated administration multiple times a day?

Accepted Answer

These drugs are rapidly metabolized by the liver, necessitating repeated drug administration (usually two to four times a day) to maintain a therapeutic response.

Question 8

The effects of histamine on the vasculature are that it:

Accepted Answer

Histamine usually produces a transient drop in blood pressure because it dilates small blood vessels and capillaries.

Question 9

Life-threatening arrhythmias can occur with astemazole and terfenadine because of:

Accepted Answer

On the ECG, prolongation of the QTc interval reflects a change in cardiac conduction that makes it possible for life-threatening ventricular arrhythmias to occur. The mechanism is a direct interaction with selective ion channels (K, Na, Ca) in the myocardium that interrupts normal cardiorhythm.

Question 10

A person allergic to chocolate may develop a migraine headache because:

Accepted Answer

Dilation of cerebral blood vessels stimulates pain receptors in the skull.

Question 11

What will happen to mast cells once an individual is first exposed to an allergen?

Accepted Answer

The first time a person comes into contact with tree pollen, dust mites, or other allergens (antigens), white blood cells produce antibodies, specifically IgE immunoglobulin. The IgE attaches to the surface of mast cells. On the repeated exposure, when an antigen comes into contact with the skin or lungs or enters the bloodstream of sensitized individuals, the allergen binds to the IgE and triggers a release of mast cell contents.

Question 12

The best time to administer cromolyn sodium is:

Accepted Answer

Since this drug has no effect on histamine receptors, cromolyn sodium must be administered before histamine release has begun.

Question 13

Why would Dr.Smith not prescribe an antihistamine for his patient with asthma?

Accepted Answer

Antihistamines are not therapeutically useful in asthmatics because the intensity and nature of the allergic response requires an antiallergy approach.

Question 14

Why shouldn't oral cromolyn dosage forms be taken with fruit juice or milk?

Accepted Answer

Fruit juice, milk, or food will inhibit dissolution and absorption of the drug and therefore should not be consumed until 0.5 hour after dosing.

Question 15

Side effects associated with antihistaminics are:

Accepted Answer

The most common side effects produced by the antihistaminics are drowsiness and sedation. Another frequently occurring side effect is dry mouth (xerostomia).

Question 16

Antihistaminics can be used in cold remedies because of the anticholinergic properties responsible for:

Accepted Answer

Antihistaminics are frequently found in cold remedies and cough syrups because of their ability to dry nasal secretions.

Question 17

Vertigo and nausea can be treated with these antihistamine medications:

Accepted Answer

Dimenhydrinate and meclizine exert a unique action in the brain to relieve vertigo and motion sickness and the nausea that accompanies it.

Question 18

Which type of histamine receptor is located on blood vessels,bronchiolar smooth muscle,and intestinal smooth muscle and is used to mediate allergic reactions?

Accepted Answer

Histamine interacts with postsynaptic H₁-receptors, located on blood vessels, bronchiolar smooth muscle, and intestinal smooth muscle, to mediate allergic reactions.

Question 19

What unexpected adverse effect can elderly patients experience when taking an antihistaminic?

Accepted Answer

In patients over 60 years of age, paradoxical stimulation rather than sedation can occur and may warrant dose reduction to eliminate this adverse experience.

Quiz 31: Antihistaminic Drugs and Mast Cell Release Inhibitors