What is Brompheniramine?

Brompheniramine: An Overview

Brompheniramine is a first-generation antihistamine that blocks histamine H1 receptors to reduce sneezing, itching, and rhinorrhea, with additional anticholinergic (drying) and sedative effects. 1

Mechanism of Action and Pharmacology

• Brompheniramine maleate is an alkylamine class antihistamine that competes with histamine for H1 receptor sites on effector cells, antagonizing allergic responses including vasodilation, increased vascular permeability, and mucus secretion in nasal tissue 1
• It is well absorbed from the gastrointestinal tract, with peak plasma concentration after a single 4 mg oral dose reached in 5 hours; urinary excretion is the major route of elimination 1
• In children, the terminal elimination half-life is approximately 12.4 hours, with peak concentrations occurring at about 3.2 hours after administration 2

Clinical Uses

• Brompheniramine is recommended for treating acute cough, post-nasal drip, and throat clearing associated with the common cold, often combined with pseudoephedrine for enhanced symptom relief 3
• It is effective for treating symptoms of allergic rhinitis, including sneezing, rhinorrhea, and nasal congestion 4
• It has demonstrated efficacy in reducing rhinovirus cold symptoms including nasal secretions, rhinorrhea, sneezing, and cough compared to placebo 5
• First-generation antihistamines like brompheniramine are preferred over newer generation antihistamines for treating cold symptoms due to their anticholinergic properties 3

Dosage Forms and Administration

• Available in various formulations, including extended-release preparations 4
• For adults, typical dosing is 4 mg every 4-6 hours or 8-12 mg twice daily in extended-release formulations 4
• In children, a single 4 mg dose produces prompt and long-lasting peripheral H1-blockade, with significant antihistamine effects lasting up to 30 hours 2

Side Effects and Precautions

• Common side effects include sedation, drowsiness, and impaired performance, which can affect driving ability and cognitive function 1, 6
• Should be used with caution in patients with bronchial asthma, narrow-angle glaucoma, gastrointestinal obstruction, or urinary bladder neck obstruction due to its anticholinergic effects 1
• May have additive effects when combined with alcohol and other CNS depressants 1
• First-generation antihistamines like brompheniramine can cause performance impairment in school and driving that may exist without subjective awareness of sedation 3
• These undesirable effects cannot be eliminated by administration only at bedtime due to prolonged plasma half-life 3

Special Populations

• Should be used with caution in elderly patients, who are more likely to experience dizziness, sedation, and hypotension from antihistamines 1
• Dose selection for elderly patients should be cautious, starting at the lower end of the dosing range 1
• Safety in pregnancy has not been well established; animal reproduction studies have not shown evidence of impaired fertility or fetal harm, but human studies are lacking 1
• Contraindicated in nursing mothers due to higher risk of antihistamine intolerance in infants, particularly newborns and premature infants 1

Comparative Efficacy

• Extended-release brompheniramine (12 mg twice daily) has been shown to provide significantly better relief of allergic rhinitis symptoms than terfenadine (60 mg twice daily) 4
• Unlike newer generation non-sedating antihistamines, which are ineffective for reducing cough in common cold, first-generation antihistamines like brompheniramine are effective for this purpose 3
• Dexbrompheniramine (a derivative) combined with pseudoephedrine has shown effectiveness for cough severity, while non-sedating antihistamine/pseudoephedrine combinations did not show similar benefits 7

Clinical Pearls

• Brompheniramine may interact with monoamine oxidase (MAO) inhibitors, potentially prolonging and intensifying anticholinergic effects 1
• When treating common cold symptoms, brompheniramine is often more effective when combined with a decongestant like pseudoephedrine 3, 8
• The anticholinergic effects of brompheniramine may explain its better control of rhinorrhea compared to second-generation antihistamines 3