High dose astemizole in children with allergic rhinoconjunctivitis

In a double blind manner 38 children with hayfever due to birch pollinosis and weighing 25–80 kg (mean 45 kg) were treated with either astemizole 5 mg/d or placebo for 2 wks before the start of the birch pollen season. At the start of the season all children were given astemizole in doses increasing every week, i. e. 5, 10, 20 and 40 mg/d. This part of the study was blind in that patients did not know the actual dose administered and the physiscians did not know the plasma concentrations of the drug. Blood was drawn before the start of the medication and after each week in the single blind phase of the trial. Despite the long half‐life of astemizole. prophylactic treatment gave no improvement during the first week of the pollen season. Increasing daily doses from 0. 1 mg/kg body weight gave i'ewer hayfever symptoms up to 0. 25 mg/kg, corresponding to a plasma concentration of 4 ng/ml of astemizole plus hydroxyluted metabolites. Still higher doses up to 40 mg/d, corresponding to 0. 5–1. 6 mg/kg/d. gave littie improvement. Sedation and other side effects did not increase with higher doses. Analyses of various laboratory tests did not reveal any abnormalities that were judged to be a result of the medication. However, liver enzymes increased during the treatment period although all values were within normal limits. Thus, astemizole is safe even in higher doses, but neither prophylactic treatment nor daily doses above 0. 25 mg/kg/d improve treatment results in hayfever. The statistical lime series model used correlating symptoms with pollen exposure allowed a good evaluation of the dose‐response of astemizole in hayfever despite the limited number of patients