Diphenhydramine?

Question 0

What is the mechanism of action of Diphenhydrmanine?

Answer 0

Competes with Histamine to Antagonizes H1 receptors on effect cell in GI tract, blood vessels, and resp tract.

Question 1

What is the drug classification of Diphenhydramine?

Answer 1

“First generation antihistamine H1 receptor antagonist”

Question 2

What is the onset, DOA, E1/2T, VD, and metabolism of Benadryl?

Answer 2

DOA = 4-6 hrs
E1/2 life = 2-8 hrs
Vd = high
78% PB”

“Hepatic metabolism, first pass effect. Elim in urine.
Inhibits Cyp2D6”

Question 3

What are the Indications of Benadryl?

Answer 3

“Prevent or treat allergic/hypersensitivity reactions to blood, drugs, or allergens. (given with epi in anaphylaxis)
Tx motion sickness
Tx parkinsonism
Sedative/mild hypnotic
Antiemetic
Antipruritic, antitussive, anticholinergic
Topic anesthetic
Tx antipsychotic induced EPS
Given with cimetidine (H2 blocker) and steroids for prophylaxis to those with genetic predisopostion to latex allergy, dye studies, and chemo.”

Question 4

What are the Adverse effects of Benadryl?

Answer 4

“Somnolence, dizziness, seizures, irritiabily, nervousness, fatigue, photosensitivity, blurred vision, paradoxical excitement in peds, euphoria, confusion
Delayed emergence if given at end of case.
Dry mouth
Hypotension, tachycardia, palpitations
Thickening of bronchial secretions
Urinary retention, epigastric distress, constipation, N/V/D, anorexia, weight gain
Hemolytic anemia, thrombocytopenia, agranulocytosis,
Tremor, paresthesia, rash”

Question 5

What are the contraindications of Benadryl?

Answer 5

“Driving or operating heavy machinery
Premature infants, neonates, nursing moms,
Hypersensitivity
Caution in : LRI, hyperthyroid, CV disease, HTN, glaucoma, symptomatic prostatic hypertrophy, pyloroduodenal obstruct”