Comparison of CNS adverse effects between astemizole and chlorpheniramine in children: a randomized, double-blind study.

Objective: To assess the central nervous system side effects of chlorpheniramine and astemizole in children.

Design: Prospective, randomized, double-blind cross-over study.

Setting: Children were recruited from the out-patient allergy clinic and from respondents to an advertisement in a local newspaper. The study was conducted in the outpatient clinics of the ambulatory care services of the Children's Hospital of Eastern Ontario.

Patients, participants: Children 8-16 years of age, with isolated allergic rhinitis or hay fever, were eligible for the study. We excluded children with: (1) chronic conditions (specifically asthma, atopic dermatitis, learning disabilities, or current treatment with oral corticosteroid medication); (2) known allergy to the study medications; (3) recent use of any antihistamine medication. One hundred and three children entered the study and 92 completed it.

Interventions: Children were stratified by age and randomly allocated to treatment with one of the two medication sequences. Over a period of 13 weeks both groups had 1 week of baseline studies, 3 weeks of one study medication, either chlorpheniramine or astemizole, a 6-week wash-out period and then 3 weeks of the other study medication for a second treatment period.

Main outcome measures: Attention span (continuous performance test), short-term auditory and visual memory (visual aural digit span test), visual memory for geometric shapes (Benton visual retention test), motor coordination and visual-motor integration (grooved pegboard test), tapping speed and fine motor coordination (finger tapping test), physical side effects (such as sleepiness and dizziness), and compliance.

Results: One hundred and three patients were enrolled in the study, 92 (89%) completed the study. There were no significant drug effects on the visual retention test and the continuous performance test. On the visual aural digit span test, patients treated with astemizole scored higher than at baseline. There were no clinical or statistical differences in adverse effects between the two medications or between each medication and baseline.

Conclusions: The two antihistamines studied had no adverse effects on the performance of children.