Diphenhydramine (Benadryl)

Question 1

Diphenhydramine (Benadryl) Class

Answer 1

Antihistamine (H1 Blocker)

Question 2

MOA of Diphenhydramine (Benadryl)

Answer 2

Blocks H1 histamine receptors in the respiratory tract, blood vessels, and GI smooth muscle; decreases motion sickness. Reverses extrapyramidal reactions.

Question 3

Indications for Diphenhydramine (Benadryl)

Answer 3

Symptomatic relief of allergies, allergic reactions, and anaphylaxis, blood adm reactions, motion sickness, and relief of acute dystonic reactions caused by phenothiazines;may be useful in phenothiazine OD’s.

Question 4

Contraindications for Diphenhydramine (Benadryl)

Answer 4

Hypersensitivity to antihistamines, newborns or premature infants, breastfeeding. Pt w/asthma, narrow-angle glaucoma, or taking MAOI’s. Use with caution in infants, children, and older adults.

Question 5

Adverse Reactions of Diphenhydramine (Benadryl)

Answer 5

Drowsiness, Sedation, Seizures, dizziness, headache, blurred vision, wheezing, thickening of bronchial secretions, palpitations, hypotension, dysrhythmias, dry mouth, diarrhea, N/V, hallucinations confusion. Paradoxical CNS excitation can occur in children.

Question 6

Dosage for Diphenhydramine (Benadryl)

Answer 6

Adults: 25-50mg, IM/IV/IO

Peds: 1-2mg/kg IV/IO/IM, slowly. If PO, 5mg/kg per 24hrs.

Question 7

Duration of Action of Diphenhydramine (Benadryl)

Answer 7

Onset: 15-30 mins

Peak: 1hr

Duration: 3-12hrs