Diphenhydramine hydrochloride

Question 1

What is the trade name of Diphenhydramine hydrochloride?

Answer 1

Benadryl

Question 2

What is the classification of diphenhydramine?

Answer 2

• anti-histamine
• anti-emetic
• anti-vertigo
• anti-dyskinetic
• sedative-hypnotic

Question 3

How is diphenhydramine supplied?

Answer 3

50 mg/mL ampule

Question 4

What is the MOA (pharmacodynamics) of

diphenhydramine?

Answer 4

• Antihistamine: Competes for H1 receptor sites on the smooth muscle of the bronchi, GI tract, uterus, and large blood vessels. By binding to cellular receptors, they prevent access of histamine and suppress histamine induced allergic symptoms even though they do not prevent release.
• Produces anticholinergic, antipruritic, antitussive, antiemetic, antidyskinetic and sedative effects

Question 5

List the indications for diphenhydramine?

Answer 5

Allergic reaction
Anaphylaxis
Dyskinesia from anti-psychotic
Anti-emetic agent

Question 6

What is the dosage for diphenhydramine?

Answer 6

Adult: 25 - 50 mg IVP/IM/PO q4hrs prn

Pediatric: 1mg/kg SIVP/IM q4Hrs prn

Question 7

List the contraindications for diphenhydramine.

Answer 7

Hypersensitivity

Acute asthma attack

Breast feeding

Question 8

What is a precaution (relative contraindication) in the use of diphenhydramine?

Answer 8

Asthma – Ensure it’s a true allergic reaction and not an asthma attack.

Question 9

What are some things to consider before administering diphenhydramine?

Answer 9

Children under 6 years of age may experience paradoxical hyper-excitability.

Antiemetic, antivertigo, antidyskinetic: Central anti-muscarinic actions of antihistamines are responsible for these actions.

Sedative/hypnotic: mechanism unknown.