What is brompheniramine (Bromphed)?

Brompheniramine (Bromphed): A First-Generation Antihistamine

Brompheniramine (Bromphed) is a first-generation antihistamine that acts as an H1-receptor antagonist with significant anticholinergic properties, used primarily for treating symptoms of allergic rhinitis, common cold, and upper airway cough syndrome. 1

Mechanism of Action

• Brompheniramine belongs to the alkylamine class of antihistamines and works by competing with histamine for H1-receptor sites on effector cells, antagonizing allergic responses including vasodilation, increased vascular permeability, and increased mucus secretion 1
• Unlike newer generation antihistamines, brompheniramine has significant anticholinergic (drying) effects that contribute to its efficacy in treating rhinorrhea, particularly in non-allergic conditions 2
• It also possesses sedative properties due to its ability to cross the blood-brain barrier 1, 3

Pharmacokinetics

• Brompheniramine is well absorbed from the gastrointestinal tract with peak plasma concentrations reached in approximately 3-5 hours after oral administration 1, 4
• It has a long half-life of approximately 24.9 hours and a large volume of distribution (11.7 L/kg) 4
• Elimination occurs primarily through urinary excretion, mostly as products of biodegradation, with the liver being the main site of metabolic transformation 1

Clinical Applications

• Upper Airway Cough Syndrome (UACS): First-generation antihistamines like brompheniramine are recommended as first-line empiric therapy for UACS due to their anticholinergic effects 2
• Common Cold: Brompheniramine has proven efficacy in reducing rhinorrhea, sneezing, and cough associated with rhinovirus colds 2, 5
• Allergic Rhinitis: Effective for treating symptoms of allergic rhinitis, particularly when combined with decongestants like pseudoephedrine 2
• Post-viral Upper Respiratory Infections: Often combined with pseudoephedrine for treating cough and nasal symptoms associated with post-viral URIs 2

Dosing

• For adults, typical dosing is 4 mg every 4-6 hours or 8-12 mg of sustained-release formulations twice daily 3
• Often combined with pseudoephedrine (as in Bromphed-D) for enhanced decongestant effects 2

Advantages Over Newer Antihistamines

• First-generation antihistamines like brompheniramine are more effective than newer generation antihistamines for treating cough associated with the common cold due to their anticholinergic properties 2
• The ACCP guidelines specifically recommend first-generation antihistamines over newer generation nonsedating antihistamines for treating cough associated with common cold 2

Side Effects and Precautions

• Sedation is the primary side effect, with potential for impaired performance in tasks requiring alertness 3, 4
• Performance impairment may occur without subjective awareness of sedation, potentially affecting driving and school performance 2
• Anticholinergic effects include dry mouth, dry eyes, constipation, urinary retention, and potential exacerbation of narrow-angle glaucoma 2
• Sustained-release preparations may have similar performance-impairing effects as immediate-release forms 3
• Use with caution in patients with glaucoma, prostatic hypertrophy, or urinary retention 2

Comparative Efficacy

• Brompheniramine has similar affinity for muscarinic receptors as chlorpheniramine, making them comparable in anticholinergic effects 6
• Both are significantly more anticholinergic than second-generation antihistamines like terfenadine 6
• When combined with pseudoephedrine, brompheniramine provides effective relief of both histamine-mediated symptoms and nasal congestion 1