Clinical significance of tricyclic antidepressant plasma levels

Review of the literature indicates that measurements of tricyclic antidepressant plasma levels have great potential for clinical application. Their use is currently limited mainly by the difficulty in obtaining quality laboratory determinations in most geographic areas. Plasma levels are most valuable in treatment of patients who have problems with lack of response to the drugs, placebo response, noncompliance, multidrug effects, and changes associated with aging. Clinical application of steady-state plasma level ranges should be limited to patients with endogenous depression, since data are very limited for other varieties of depressive illness.