Platelet [3H]imipramine and [3H]paroxetine binding in depressed patients.

[3H]Paroxetine and [3H]imipramine binding to blood platelet membranes was simultaneously measured in 63 control subjects and 18 patients with DSM-III-R criteria for major depression with melancholia. Both binding sites showed significantly different (p < 0.001) maximum binding (Bmax) and equilibrium dissociation constant (Kd) values. Age was not correlated with either [3H]imipramine Bmax or Kd values, but a negative correlation was found between [3H]paroxetine Bmax and age in healthy controls. Furthermore, depressed patients showed significantly lower [3H]imipramine Bmax values (p < 0.001) and higher Kd values (p < 0.001) in comparison to the control group. No differences were observed in [3H]paroxetine Bmax and Kd values between the two groups.