Case series: clonidine has no systematic effects on PR or QTc intervals in children.

This study retrospectively examined the effects of clonidine, both alone and combined with psychostimulants, on the electrocardiograms (ECGs) of children and adolescents. Two pediatric cardiologists, blinded to treatment condition, examined pre- and posttreatment ECGs in 42 subjects treated with clonidine for attention-deficit/hyperactivity or tic disorder. While ECG variability was found, it did not appear to be related to any systematic effect of clonidine, either alone or in combination with psychostimulants. These data do not rule out the possibility of rare idiosyncratic reactions to clonidine with or without psychostimulants, though none occurred in this sample.