An open-label study of duloxetine for the treatment of major depressive disorder: comparison of switching versus initiating treatment approaches.

This study compared the stabilized duloxetine dose through approximately 12 weeks of treatment in patients initiating duloxetine therapy with that in patients switching to duloxetine from selective serotonin reuptake inhibitors or venlafaxine. All patients met Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria for major depressive disorder. Patients (n = 112) exhibiting suboptimal response or poor tolerability to their current antidepressant medication (citalopram, escitalopram, fluvoxamine, paroxetine, sertraline, or venlafaxine) were switched to duloxetine 60 mg once daily (QD) without intermediate tapering or titration ("switching" group). A comparator group (n = 137), comprising patients not currently receiving antidepressant medication, was randomized to receive duloxetine 30 or 60 mg QD ("initiating" group). At the end of week 1, patients receiving 30 mg QD had their dose increased to 60 mg QD. During the remainder of the study, each patient's duloxetine dose could be titrated on the basis of degree of response within a range from 60 to 120 mg QD, with 90 mg QD as an intermediate dose. At the study end point, approximately one third of the patients in each treatment group were stabilized at each of the 3 studied duloxetine doses (60, 90, and 120 mg QD), and the distribution of stabilized doses among patients initiating duloxetine therapy did not differ significantly from that observed in patients switching to duloxetine. The efficacy of duloxetine in patients switching from selective serotonin reuptake inhibitor/venlafaxine did not differ significantly from that observed in untreated patients initiating duloxetine therapy (baseline-to-end point mean changes: 17-Item Hamilton Rating Scale for Depression total score, -13.1 vs. -13.5; Hamilton Rating Scale for Anxiety, -10.6 vs. -10.3; and Clinical Global Impression of Severity, -2.22 vs. -2.38, respectively). The rate of discontinuation caused by adverse events among patients switched to duloxetine was significantly lower than that in patients initiating duloxetine therapy (6.3% vs. 16.1%, P = 0.018). Treatment-emergent adverse events occurring in more than 10% of patients in both treatment groups were nausea, headache, dry mouth, insomnia, diarrhea, and constipation. In the first week of therapy, patients switched to duloxetine reported significantly lower rates of headache and fatigue compared with patients initiating duloxetine. Thus, the efficacy of duloxetine in switched patients was comparable to that observed in patients initiating duloxetine therapy. Immediate switching from a selective serotonin reuptake inhibitor or venlafaxine to duloxetine (60 mg QD) was well tolerated.