[Tricyclic antidepressant plasma levels in depression: a practical guide].

BACKGROUND: Plasma levels can be used to monitor the clinical efficacy of tricyclic antidepressants (TCAs). In practice, the interpretation of plasma levels can be problematical, for several reasons: varying time-intervals between ingestion and blood sampling, the number of times per day a particular antidepressant is administered, the presence of active metabolites and the use of slow-release substances. AIM: To present realistic recommendations regarding the interpretation of plasma levels of TCA in clinical practice. METHOD: We studied the relevant literature. CONCLUSION: On the basis of the literature we make the following recommendations: