Structural and concentration effects on the deposition of tricyclic antidepressants in human hair

In order to elucidate the possibility of a long-term compliance analysis the hair samples of 56 patients, who were under a permanent treatment with tricyclic antidepressants, were analyzed for amitriptyline, clomipramine, doxepine, imipramine and maprotiline as well as their nor-metabolites. The hair concentrations varied between 0.4 and 40 ng/mg with no strong difference between the five drugs. In comparison to the therapeutic plasma levels described in literature the nor-metabolites always accumulate less in hair than drugs. No correlation was found between the hair concentration and the daily dose. The investigation of the full hair length in 3-cm sections for several examples of all five drugs shows that they can be detected in normally kept hair at least 1 year after intake.