Venlafaxine and treatment-resistant depression.

Treatment-resistant depression (TRD) is an important clinical problem. This paper briefly reviews the definition of TRD and summarizes methodological issues that pertain to treatment research. Recent studies of venlafaxine treatment for TRD also are reviewed. It is concluded that venlafaxine at higher doses is a reasonably well-tolerated and an effective alternative for patients with TRD and typically should be used before tricyclic antidepressants or monoamine oxidase inhibitors. Further research is needed to confirm the prediction that switching a SSRI nonresponder to venlafaxine is a more effective strategy than switching to a second SSRI. The relative merits of switching from a SSRI to venlafaxine versus adding a norepinephrine reuptake inhibitor also warrant careful study.