Diphenhydramine HCL Flashcards

1
Q

Generic Name:

A

Diphenhydramine HCL

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2
Q

Trade Name:

A

Benadryl

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3
Q

Supplied:

A

50mg/mL vial

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4
Q

Class:

A

Antihistamine; anticholinergic

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5
Q

Mechanism of Action:

A
  • Blocks cellular histamine receptors, but does not prevent histamine release; results in decreased capillary permeability and decreased vasodilation, as well as prevention of bronchospasm.
  • Has some anticholinergic effects.
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6
Q

Indications and Field Use:

A
  • Anaphylaxis (2nd line)
  • Phenothiazine reactions (extrapyramidal symptoms)
  • Antimetic
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7
Q

Contraindications:

A
  • Known hypersensitivity to diphenhydramine or drugs of similar chemical structure.
  • Newborn or premature infants; nursing mothers
  • Considerable caution in patients with glaucoma, acute narrow angle; stenosing or obstructive diseases of the GI tract: bronchial asthma: hyperthyroidism: cardiovascular disease or hypertension; age greater than 60 years (all relative benefit vs risk).
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8
Q

Adverse Reactions:

A

CV: Hypotension; palpitations; arrhythmias; hemolytic anemia.

Resp: Anaphylaxis; thickening of bronchial secretions, tightness in chest; wheezing; nasal stuffiness.

CNS: Sedation; visual disturbances; seizures.

GU/GI: Urinary frequency or retention; vomiting.

Children: In children, may cause paradoxical CNS excitation, seizures, palpitations, thickening of bronchial secretions.

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9
Q

Incompatibilities/Drug Interactions:

A
  • Additive effects with alcohol and other CNS depressants (hypnotics, sedatives, tranquilizers, etc.)
  • MAO inhibitors prolong and intensify anticholinergic (drying) effects.
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10
Q

Adult Dosage: Anaphylaxis:

A

25-50mg slow IV push or deep IM

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11
Q

Adult Dosage: Extrapyramidal symptoms and antiemetic:

A

10-50mg IV or deep IM, dose should be individualized according to the needs and patient response.

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12
Q

Pediatric Dosage:

A

1.0 - 1.25 mg/kg slow IV push

May also be given deep IM

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13
Q

Routes of Administration:

A

IV/IO, Deep IM

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14
Q

Onset of Action:

A

IV 5-10 minutes

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15
Q

Peak Effects:

A

1 hour

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16
Q

Duration of Action:

A

3-6 hours

17
Q

Arizona Drug Box Minimum Supply:

A

50mg

18
Q

Special Notes:

A
  • Not used in newborn or premature infants; used in pregnancy only if clearly needed.
  • In anaphylaxis, used as a 2nd line treatment after epinephrine and steroids.