Identification and treatment of antidepressant tachyphylaxis.

Antidepressant tachyphylaxis describes a condition in which a depressed patient loses a previously effective antidepressant treatment response despite staying on the same drug and dosage for maintenance treatment. It has been suggested that antidepressant tachyphylaxis is a form of relapse related to evolving drug tolerance, but it is also clear that there are other possible reasons for the loss of treatment response unrelated to tolerance, such as medication nonadherence. It has been reported that depressed patients with "true" antidepressant tachyphylaxis may be less responsive to new treatment interventions. Therefore, it is important to identify these patients as part of a comprehensive treatment planning process.