NATIONAL
CALIFORNIA
VENTURA
category
mechanism
- Competes with histamine for H1-receptor sites
- Anticholinergic and sedative effects are also significant
indications
- Symptomatic relief of allergic symptoms caused by histamine release
- Acute dystonic reaction (involuntary contractions of muscles of the extremities, face, neck, abdomen, pelvis, or larynx)
contraindications
- Use with caution in patients with severe liver disease, angle-closure glaucoma, seizure disorders, prostate hyperplasia or peptic ulcers.
- Geriatric patients are more susceptible to adverse drug reactions and anticholinergic effects.
dosing
Adult
IV, IM, IO: 50 mg
Pediatric
IV, IM, IO: 1 mg/kg; maximum 50 mg
administration
IV, IM: Injection solution is for IV or deep IM administration only. For IV administration, inject at a rate ≤25 mg/minute. Local necrosis may result with SubQ or intradermal use.
onset
rapid
peak
2 hours
duration
10-12 hours
notes
- Paradoxical effects: May cause paradoxical stimulatory CNS effects including irritability, paradoxical excitation, and insomnia, especially in young children
- Dystonic reaction: Antipsychotics, antiemetics, and antidepressants are the most common causes of drug-induced dystonic reactions. Acute dystonic reactions have been described with every antipsychotic. Alcohol and cocaine use increase risk.
dosage form
Injection solution: 50 mg/mL (1 mL vial)
brand name
Benadryl
adverse reactions
- Anticholinergic (antimuscarinic) effects
- Blurred vision
- Xerostomia (dry mouth)
- Urinary retention
- Impotence
- Tachycardia
- Gastrointestinal effects (eg, nausea, constipation)
- CNS effects (eg, agitation, confusion, cognitive dysfunction, delirium
- Central Nervous System
- CNS depression
- Sedation
- Fatigue
- Lack of concentration, and memory impairment
structure
