Maximum Dose of Brompheniramine for Adults
The maximum recommended dose of brompheniramine for a typical adult with no significant medical history is 24 mg per day, typically administered as 4-12 mg at bedtime or divided into multiple doses throughout the day. 1
Standard Adult Dosing
The typical adult oral dose ranges from 4-12 mg per day, with the higher end (12 mg) often given as a single nighttime dose when used as adjunctive therapy for conditions like urticaria 1
Brompheniramine can be administered in divided doses, with studies examining both 4 mg immediate-release and 12 mg sustained-release formulations 2
Peak serum concentrations occur at approximately 3 hours after administration, with a prolonged half-life of approximately 25 hours in normal adults, allowing for less frequent dosing 3
Clinical Pharmacology Supporting Dosing
The antihistaminic effect is prolonged, with significant suppression of wheal and flare responses lasting 3-48 hours after a single dose, and pruritus suppression documented at 9-24 hours 3
The large volume of distribution (11.7 L/kg) and extended half-life (24.9 hours) support once or twice daily dosing rather than more frequent administration 3
Performance and Safety Considerations
Brompheniramine 4 mg impairs psychomotor performance from 1.5 to 3 hours post-dose, while the 12 mg sustained-release formulation shows impairment at 1.5 hours 2
Subjective drowsiness typically lasts up to 6 hours after brompheniramine administration, with tolerance developing by the second day of repeated dosing 4
The sedative effects make brompheniramine particularly useful as a nighttime adjunct to non-sedating antihistamines, though clinical benefit may be limited if H1 receptors are already saturated 1
Special Populations Requiring Dose Adjustment
Dose reduction should be considered in patients with moderate renal insufficiency, as clearance may be impaired 1
Brompheniramine is contraindicated in severe hepatic disease because sedative effects are inappropriate and may precipitate hepatic coma 1
Additional contraindications include angle-closure glaucoma, prostatic hypertrophy, and urinary retention due to anticholinergic properties 1
Drug Interactions and Precautions
Avoid concomitant use with monoamine oxidase inhibitors (MAOIs) and other medications with anticholinergic effects 1
Anticholinergic effects are particularly problematic in elderly patients, who may experience confusion, urinary retention, or other adverse effects even at standard doses 1
Use during pregnancy should be avoided, especially in the first trimester, despite a long historical safety record 1
Practical Dosing Algorithm
For acute allergic reactions: Start with 4 mg orally, which can be repeated every 4-6 hours as needed, not exceeding 24 mg in 24 hours
For chronic conditions like urticaria: Consider 4-12 mg as a single nighttime dose to minimize daytime sedation while providing symptom control 1
When used as adjunctive therapy in anaphylaxis: Administer alongside epinephrine and hydrocortisone, with pediatric dosing varying by age (10 mg for >12 years) 1
Monitor for excessive sedation particularly during the first 1.5-6 hours after administration, and counsel patients about impaired performance during this window 2, 4