Long-term monitoring of tricyclic antidepressant plasma concentrations.

Plasma levels of antidepressant drugs were measured in 17 depressed patients at roughly monthly intervals over follow-up periods of three to 26 months. Good results in seven were associated with small fluctuations in level from visit to visit, while big fluctuations were associated with poor outcome. Such fluctuations were probably from poor compliance or drug interaction from self-medication. Severe side effects and cardiotoxicity were associated with high levels.