Chapter 70: Antihistamines

Chapter 70: Antihistamines

 

Complete Chapter Questions With Answers

 

Sample Questions Are Posted Below

 

MULTIPLE CHOICE

 

1. A pregnant patient asks the nurse if she can take antihistamines for seasonal allergies during her pregnancy. What will the nurse tell the patient?

a.	Antihistamines should be avoided unless absolutely necessary.
b.	Second-generation antihistamines are safer than first-generation antihistamines.
c.	Antihistamines should not be taken during pregnancy but may be taken when breast-feeding.
d.	The margin of safety for antihistamines is clearly understood for pregnant patients.

 

 

ANS:  A

Antihistamines are pregnancy Category C, with debate currently occurring regarding degree of effects on the fetus. They should be avoided unless absolutely necessary. All antihistamines have adverse effects on the fetus. Antihistamines can be excreted in breast milk. The margin of safety of antihistamines in pregnancy is not clear, so these agents should be avoided unless a clear benefit of treatment outweighs any risks.

 

PTS:   1                    DIF:    Cognitive Level: Application           REF:   p. 843

TOP:   Nursing Process: Implementation

MSC:  NCLEX Client Needs Category: Physiologic Integrity: Physiologic Adaptation

 

2. A family is preparing for travel and the parents report that their 5-year-old child has frequent motion sickness. The nurse will tell the parents to ask the provider about which antihistamine to help prevent symptoms?

a.	Desloratadine [Clarinex]
b.	Dimenhydrinate [Dramamine]
c.	Hydroxyzine [Vistaril]
d.	Promethazine [Phenergan]

 

 

ANS:  B

Some antihistamines, including dimenhydrinate and promethazine, are labeled for use in motion sickness. Promethazine, however, is contraindicated in children under age 2 years and should be used with caution in children older than 2 years because of the risks for severe respiratory depression. Desloratadine and hydroxyzine are not used for motion sickness.

 

PTS:   1                    DIF:    Cognitive Level: Application           REF:   pp. 842-844

TOP:   Nursing Process: Assessment

MSC:  NCLEX Client Needs Category: Physiologic Integrity: Pharmacologic and Parenteral Therapies

 

3. A nurse is teaching a group of nursing students about antihistamines. Which statement by a student indicates an understanding of the mechanism of action of the antihistamines?

a.	“Antihistamines block H1 receptors to prevent actions of histamine at these sites.”
b.	“Antihistamines block release of histamine from mast cells and basophils.”
c.	“H1 antagonists can bind to H1 receptors, H2 receptors, and muscarinic receptors.”
d.	“First-generation antihistamines are more selective than second-generation antihistamines.”

 

 

ANS:  A

Antihistamines block H₁ receptors to prevent the actions of histamine. They do not block the release of histamine. H₁ antagonists do not bind to H₂ receptors; they do bind to muscarinic receptors. Second-generation antihistamines are more selective than first-generation antihistamines.

 

PTS:   1                    DIF:    Cognitive Level: Application           REF:   pp. 842-844

TOP:   Nursing Process: Assessment

MSC:  NCLEX Client Needs Category: Physiologic Integrity: Pharmacologic and Parenteral Therapies

 

4. A patient who has chronic allergies takes loratadine [Claritin] and develops a severe reaction to bee stings. The patient asks the nurse why the antihistamine did not prevent the reaction. What will the nurse say?

a.	“Allergy symptoms that are severe are caused by mediators other than histamine.”
b.	“H1 blockers do not prevent the release of histamine from mast cells and basophils.”
c.	“Second-generation H1 blockers contain less active drug and do not work in severe reactions.”
d.	“Severe allergic reactions occur through actions on muscarinic receptors.”

 

 

ANS:  A

Severe allergic reactions with symptoms of anaphylaxis are caused by mediators other than histamine, so the benefits of antihistamines are limited. H₁ blockers do not block the release of histamine, but this is not why they are not effective in anaphylaxis. Second-generation agents are as effective as first-generation agents in allergic reactions mediated by histamine; neither is effective for treating anaphylaxis.

 

PTS:   1                    DIF:    Cognitive Level: Application           REF:   p. 843

TOP:   Nursing Process: Implementation

MSC:  NCLEX Client Needs Category: Physiologic Integrity: Pharmacologic and Parenteral Therapies