Imipramine binding to platelets of children with attention deficit disorder with hyperactivity.

High-affinity [3H]imipramine binding to platelets was investigated in 11 boys with attention deficit disorder and hyperactivity (ADDH) before and after 28 days of methylphenidate (MPH) treatment, and the results were compared to [3H]imipramine binding parameters (Kd, Bmax) of 10 age-matched normal boys. The binding parameters for imipramine binding sites did not differ between ADDH children and controls. Moreover, the beneficial therapeutic effect of MPH was not accompanied by any alteration in the binding values. This study is consistent with other studies that failed to demonstrate involvement of the serotonergic system in the pathophysiology of ADDH and in the therapeutic effect of MPH.