Pharmacokinetics and efficacy of chlorpheniramine in children.

Chlorpheniramine is widely used, but there is very little information about its pharmacokinetics and efficacy in children. In 11 patients with allergic rhinitis, ages 6 to 16 yr, we found a mean serum chlorpheniramine half-life of 13.1 +/- 6.3 hr, a mean volume of distribution of 7.0 +/- 2.8 L/kg, and a mean clearance rate of 7.2 +/- 3.2 ml/min/kg. Suppression of symptoms and signs of allergic rhinitis and suppression of the histamine-induced wheal and flare responses occurred when mean serum chlorpheniramine concentration ranged from 2.3 to 12.1 and 4.1 to 10.0 ng/ml, respectively. This combined with the large volume of distribution for the drug, suggest that tissue binding is an important aspect of chlorpheniramine pharmacokinetics.