The clinical pharmacology of brompheniramine in children

Background: Brompheniramine has been widely used in the treatment of allerg ic rhinitis and other disorders during the past 3 decades. There are no pub lished studies of its clinical pharmacology in children. Objectives: This study was performed to test the hypothesis that bromphenir amine would have a prompt onset of action and a 24-hour duration of action in children. Methods: Before brompheniramine 4 mg was ingested, and at intervals from 0. 5 to 30 hours thereafter, blood samples were obtained for quantitation of p lasma brompheniramine concentrations by means of HPLC. Concurrently, epicut aneous tests with histamine phosphate were performed; wheals and flares wer e traced at 10 minutes, and the areas were measured by using a computerized digitizing system. Results: In 14 children, mean age 9.5 +/- 0.4 years (SEM), the peak bromphe niramine concentration was 7.7 +/- 0.7 ng/mL, and the time at which peak co ncentrations occurred was 3.2 +/- 0.3 hours, The terminal elimination half- life was 12.4 +/- 1.1 hours, and the oral clearance was 20.2 +/- 2.1 ml/min /kg. Compared with predose areas, the wheals and flares produced by histami ne phosphate 1 mg/mL were significantly decreased from 0.5 to 30 hours and from 1 to 30 hours, respectively (P < .05), with mean maximum inhibition at 12 (52% +/- 9%) and 6 hours (72% +/- 10%), respectively. Conclusions: In children a single dose of brompheniramine produces prompt, long-lasting peripheral H-1-blockade. Revised dosage regimens may be needed in this population.