UNIT 8 Antihistamine CHAPTER 38

Question 1

What drug class is Diphenhydramine?

A. Antihistamine
B. Sulfonylurea
C. Decongestant
D. Anticholinergic

Answer 1

A. Antihistamine

Question 2

What is the action of Diphenhydramine?

Answer 2

First-generation antihistamines
◦ Diphenhydramine
◦ Action
◦ Blocks histamine, which decreases allergic response.

Uses
◦ Treat allergic rhinitis, itching (allergic reaction), prevent motion sickness, sleep aid, antitussive

Question 3

Side effects of Diphenhydramine

Answer 3

Side effects
Anticholinergic - Drowsiness, dry mouth, decreased
secretions, dizziness, blurred vision, urinary retention,
constipation
Photosensitivity
Excitability in children

Loratadine
Less drowsiness
Fewer anticholinergic side effects
Antihistamines –
diphenhydramine & loratidine

Question 4

Contraindications of Diphenhydramine

Answer 4

◦ Diphenhydramine
Contraindications/cautions
Acute asthma attack
Severe liver disease

Caution
narrow-angle glaucoma
BPH, urinary retention
Pregnancy
*constipation

Interactions
Other CNS depressants – more with
diphenhydramine
Antihistamines –
diphenhydramine & loratidine

Question 5

Assessment for Diphenhydramine

Answer 5

Assessment
◦ Baseline VS
◦ Medical/medication history
◦ S/S of urinary dysfunction
◦ Cardiac and respiratory status
◦ Environmental exposures for allergy

Question 6

Patient teaching and nursing Interventions for Diphenhydramine

Answer 6

Nursing interventions/Teaching
◦ Administer in large muscle IM
◦ Dilute and IV push over several minutes as it can cause
burning
◦ Avoid operating motor vehicles if drowsiness occurs.
◦ Avoid alcohol and other CNS depressants.
◦ Take as prescribed
◦ Use sugarless candy or gum or ice chips for temporary
relief of mouth dryness.
◦ Instruct to use caution when giving to children – can
cause excitability
◦ Older adult can be more sensitive and can cause
confusion

Question 7

What class is Loratadine

A. Antihistamine
B. Sulfonylurea
C. Decongestant
D. Anticholinergic

Answer 7

A. Antihistamine

Question 8

What is the action of Loratadine

Answer 8

Second-generation antihistamines
Nonsedating antihistamines
◦ Loratadine
◦ Action
◦ Work similarly to first-generation but without the drowsiness and anticholinergic side
effects
◦ Uses
◦ Allergic rhinitis, itching (allergic reaction).
◦ Long acting medications – longer half-life
Antihistamines
NO DROWSINESS
NO ANTICHOLINERGIC AFFECTS

Question 9

Loratadine

Answer 9

The second-generation antihistamines are frequently called nonsedating antihistamines because they have little to no sedative effect. In addition, these antihistamines cause fewer anticholinergic symptoms. Although a moderate amount of alcohol and other CNS depressants may be taken with second-generation antihistamines, many clinicians advise against such use.
The second-generation antihistamines cetirizine, fexofenadine, azelastine,
desloratadine, and loratadine have half-lives between 3 and 30 hours and are administered by nasal spray. Table 38.1 lists the first- and second-generation antihistamines used to treat allergic rhinitis.

Question 10

Which of the following is an adverse effects of Diphenhydramine?
A. Constipation
B. Drowsiness
C. Dizziness
D. Thrombocytopenia

Answer 10

D. Thrombocytopenia

Question 11

Which medication is a first-generation
antihistamine?
A. Cetirizine (Zyrtec)
B. Fexofenadine (Allegra)
C. Diphenhydramine (Benadryl)
D. Loratadine (Claritin)

Answer 11

C. Diphenhydramine (Benadryl)

Rationale: Diphenhydramine (Benadryl) is a first-generation
antihistamine. Most first-generation antihistamines cause drowsiness, dry
mouth, and other anticholinergic symptoms. The other options are drugs
that are second-generation antihistamines. These drugs have fewer
anticholinergic effects and a lower incidence of drowsiness.

Question 12

Before administering diphenhydramine
(Benadryl) to a patient, it is most important for
the nurse to assess the patient for a history of
A. allergy to penicillin.
B. hypertension.
C. diabetes mellitus type 2.
D. narrow-angle glaucoma.

Answer 12

D. narrow-angle glaucoma.

Answer: D
◦ Rationale: Diphenhydramine (Benadryl) has anticholinergic effects and
should not be used by patients with narrow-angle glaucoma

Question 13

A patient tells the nurse that he has started to take an over-the-counter antihistamine, diphenhydramine. In teaching about side effects, what is most important for the nurse to tell the patient?
a. To avoid insomnia, do not to take this drug at bedtime.
b. Avoid driving a motor vehicle until stabilized on the drug.
c. Nightmares and nervousness are more likely in an adult.
d. Medication may cause excessive secretions.

Answer 13

b. Avoid driving a motor vehicle until stabilized on the drug.