Duloxetine in the acute and long-term treatment of major depressive disorder: a placebo- and paroxetine-controlled trial

Background: Duloxetine is a balanced and potent dual reuptake inhibitor of serotonin (5-HT) and norepinephrine (NE) that has previously been shown to be effective in the acute treatment of major depressive disorder (MDD). This placebo-controlled study assesses the safety and efficacy of duloxetine (80 or 120 mg/day) and paroxetine (20 mg QD) during an initial 8-week acute phase and subsequent 6-month continuation phase treatment of MDD. Method: In this randomized, double-blind, placebo-controlled trial, adult outpatients (age ≥18 years) meeting DSM-IV criteria for MDD received placebo (n=93), duloxetine 80 mg/day (40 mg BID; n=95), duloxetine 120 mg/day (60 mg BID; n=93), or paroxetine (20 mg QD; n=86) for 8 weeks. Patients who had a ≥30% reduction from baseline in HAMD₁₇ total score during the acute phase were allowed to continue on the same (blinded) treatment for a 6-month continuation phase. Efficacy measures included the 17-item Hamilton Rating Scale for Depression (HAMD₁₇) total score, HAMD₁₇ subscales, the Montgomery-Asberg Depression Rating Scale (MADRS), the Hamilton Anxiety Rating Scale (HAMA), Visual Analog Scales (VAS) for pain, the Clinical Global Impression of Severity (CGI-S) and Patient Global Impression of Improvement (PGI-I) scales, the 28-item Somatic Symptom Inventory (SSI), and the Sheehan Disability Scale (SDS). Safety and tolerability were assessed using treatment-emergent adverse events, discontinuations due to adverse events, vital signs, ECGs, laboratory tests, and the Arizona Sexual Experiences Scale (ASEX). Results: During the acute phase, patients receiving duloxetine 80 mg/day, duloxetine 120 mg/day, or paroxetine 20 mg QD had significantly greater reductions in HAMD₁₇ total score compared with placebo. Both duloxetine (80 and 120 mg/day) and paroxetine treatment groups had significantly greater improvement, compared with placebo, in MADRS, HAMA, CGI-S, and PGI-I scales. Estimated probabilities of remission at week 8 for patients receiving duloxetine 80 mg/day (51%), duloxetine 120 mg/day (58%), and paroxetine (47%) were significantly greater compared with those receiving placebo (30%). The rate of discontinuation due to adverse events among duloxetine-treated patients (80 and 120 mg/day) did not differ significantly from the rate in the placebo group. Treatment-emergent adverse events reported significantly more frequently by duloxetine-treated patients than by patients receiving placebo were constipation (80 and 120 mg/day), increased sweating (120 mg/day), and somnolence (120 mg/day). The incidence of acute treatment-emergent sexual dysfunction in duloxetine- and paroxetine-treated patients was 46.5% and 62.8%, respectively. During the 6-month continuation phase, duloxetine (80 and 120 mg/day) and paroxetine treatment groups demonstrated significant improvement in HAMD₁₇ total score. Treatment-emergent adverse events occurring most frequently in each active treatment group during the continuation phase were viral infection (duloxetine 80 mg/day), diarrhea (duloxetine 120 mg/day), and headache (paroxetine 20 mg QD). Conclusion: These data support previous findings that duloxetine is safe, efficacious, and well tolerated in the acute treatment of MDD. Furthermore, these data provide the first demonstration under double-blind, placebo-controlled conditions that the efficacy and tolerability of duloxetine are maintained during chronic treatment.