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RESPIRATORY SYSTEM › ANTIHISTAMINES FOR SYSTEMIC USE › ANTIHISTAMINES FOR SYSTEMIC USE › Aminoalkyl ethers
diphenylpyraline
R06AA07
Forms & Strengths
- Oral capsules: 5 mg
- Oral tablets: 5 mg
- Combination pediatric liquid formulations (historically available)
Adult Dosing
- Allergic rhinitis and urticaria: 5 mg orally every 12 hours
- Maximum daily dose: 10 mg per 24 hours
Pediatric Dosing
- Children 6 to 12 years: 2.5 mg orally every 12 hours
- Children under 6 years: Safety and efficacy not established
Indications
- Symptomatic relief of allergic rhinitis
- Treatment of vasomotor rhinitis
- Management of allergic conjunctivitis
- Relief of allergic skin manifestations such as urticaria and angioedema
Mechanism of Action
- Competitive antagonism of histamine H1 receptors
- Decreases capillary permeability and prevents histamine-induced smooth muscle contraction
- Exhibits significant anticholinergic and moderate central nervous system depressant properties
Contraindications
- Hypersensitivity to diphenylpyraline or other piperidine-derivative antihistamines
- Concurrent use with monoamine oxidase inhibitors (MAOIs)
- Narrow-angle glaucoma
- Symptomatic prostatic hypertrophy
- Bladder neck obstruction
- Neonates or premature infants
Adverse Reactions
- Drowsiness, sedation, and fatigue
- Anticholinergic effects: dry mouth, blurred vision, urinary retention, and constipation
- Dizziness, headache, and paradoxical central nervous system excitation in children
- Gastrointestinal distress, nausea, and vomiting
- Hypotension, palpitations, and tachycardia
Drug Interactions
- Central nervous system depressants (alcohol, barbiturates, opioids, sedatives) enhance sedative effects
- Monoamine oxidase inhibitors (MAOIs) prolong and intensify the anticholinergic effects of antihistamines
- Drugs with strong anticholinergic properties (tricyclic antidepressants, atropine) lead to additive anticholinergic toxicity
Curated Content: Needs Vetting Before Put to Clinical Use