Duloxetine versus escitalopram and placebo: an 8-month, double-blind trial in patients with major depressive disorder

Abstract

Background: Duloxetine and escitalopram were compared in an 8-month, randomized, double-blind, placebo-controlled trial in adult outpatients meeting DSM-IV criteria for major depressive disorder (MDD). The results regarding the primary objective of the study (onset of antidepressant action) have been previously published. The current paper focuses on the longer-term (8-month) comparisons of efficacy and safety between duloxetine and escitalopram.

Research design and methods: Upon completion of the 8-week, fixed-dose, placebo-controlled, acute-treatment phase (duloxetine 60 mg/day (n = 273), escitalopram 10 mg/day (n = 274), placebo (n = 137)), patients remaining in the duloxetine (n = 188) and escitalopram (n = 208) groups were eligible for double-blind dose increases (duloxetine to 120 mg/day, escitalopram to 20 mg/day), and placebo non-responders were eligible for double-blind rescue to active drug.

Main outcome measures: Efficacy was primarily assessed using the HAMD(17). Safety/tolerability assessments included spontaneously reported adverse events (AEs), overall rates and reasons for discontinuation, laboratory analyses, and vital signs.

Results: Both drugs demonstrated similar remission rates over the course of the study, with the probability of remission reaching 70% (duloxetine) and 75% (escitalopram) at 8 months (p = 0.44). Similar improvement was observed for both duloxetine and escitalopram on efficacy measures with the exception of the sleep subscale of the HAMD(17), wherein escitalopram had a statistically significant advantage over duloxetine in improving sleep. Over the entire 8-month study, discontinuation rates differed significantly for duloxetine (62%) compared with escitalopram (55%; p = 0.02). Rates of discontinuation due to AEs did not differ significantly between duloxetine (12.8%), escitalopram (12.0%), and placebo (10.2%) (p > 0.05 all pairwise comparisons). AEs associated with duloxetine tended to emerge early in treatment (e.g., nausea, dry mouth), whereas AEs associated with escitalopram tended to emerge later in treatment (e.g., diarrhea, weight increase). The incidence of sustained hypertension was similar between drugs (1.5 vs. 1.1% patients for duloxetine and escitalopram, respectively). Statistically significant drug differences were identified in the mean changes from baseline to study endpoint for pulse (+3.05 beats per minute (bpm), duloxetine; -0.89 bpm, escitalopram; p < 0.001) and systolic blood pressure (+3.73 mmHg, duloxetine; +0.31 mmHg, escitalopram; p < 0.05), but not diastolic blood pressure (+0.81 mmHg, duloxetine; -0.24 mmHg, escitalopram; p = 0.27). At 8 months, mean change in weight was significantly higher for escitalopram compared with duloxetine (+0.61 kg, duloxetine; +1.83 kg, escitalopram; p < 0.05), however, the incidence of treatment-emergent abnormal weight gain (> or = 7% increase in weight from baseline) was similar between drugs and was significantly greater for both duloxetine and escitalopram compared with placebo.

Limitations: Because so few patients on placebo (n = 15), in comparison to duloxetine (n = 104) or escitalopram (n = 123), completed the entire 8-month study, the power to detect a difference between the active treatments and placebo after 8 weeks was significantly decreased and very likely insufficient.

Conclusion: Throughout the 8-month study, similar improvement was observed for both duloxetine and escitalopram on most efficacy measures with the exception of the sleep subscale of the HAMD(17). Drug differences were identified in safety/tolerability measures.

Trial registration: ClinicalTrials.gov NCT00073411.