- Antihistamine with anticholinergic (drying) and sedative side effects. Antihistamines appear to complete with histamine for cell receptor sites on effector cells.
- Onset - Rapid
- Peak - unknown
- Half-life - 1-4 hours
- Duration - 4-6 hours
- Antihistaminic: adjunct treatment of allergic reactions / early anaphylaxis or as an adjunct to Epinephrine in anaphylaxis.
- Motion sickness
- Hypersensitivity to antihistamines
- Premature infants
Has an atropine-like action and therefore, should be used with caution in patients with:
- A history of bronchial asthma
- Increased intraocular pressure
- Cardiovascular disease
- Lower respiratory disease
- Urticaria, drug rash, anaphylactic shock, photosensitivity, excessive perspiration, chills dryness of mouth, nose, and throat.
- Hypotension, headache, palpitations, tachycardia, extrasystoles.
- Hemolytic anemia, thrombocytopenia, agranulocytosis.
- Sedation, sleepiness, dizziness, disturbed coordination, fatigue, confusion, restlessness, excitation, nervousness, tremor, irritability, insomnia, euphoria, paresthesia, blurred vision, diplopia, vertigo, tinnitus, acute labyrinthistis, neuritis, convulsions.
- Epigastric distress, anorexia, nausea, vomiting, diarrhea, constipation.
- Thickening of bronchial secretions, tightness of chest or throat and wheezing, nasal stuffiness.
Drug to Drug
- Additive effects with alcohol and other CNS depressants (hypnotics, sedatives, tranquilizers, etc.)
- MAO inhibitors prolong and intensify the anticholinergic (drying) effects of antihistamines.
Use with caution in patients with:
- Narrow-angle glaucoma
- Stenosing peptic ulcer
- Pyloroduodenal obstruction
- Symptomatic prostatic hypertrophy
- Bladder-neck obstruction
- 25 - 50 mg IV for anaphylaxis
See BCEHS Pediatric Dosage (BCEHS Peds Dosages) recommendations for age and weight-appropriate dosing information.