Duloxetine for the treatment of major depressive disorder: safety and tolerability associated with dose escalation

Abstract

Duloxetine has demonstrated efficacy for the treatment of major depressive disorder (MDD) at a dose of 60 mg/day (given once daily). Whereas the target dose for the majority of patients is 60 mg/day, higher duloxetine doses (up to 120 mg/day) have been studied using a twice-daily dosing schedule. To further investigate the pharmacological profile of duloxetine within a once-daily dosing regimen at doses above 60 mg, we examined the safety and tolerability of duloxetine during a dose escalation from 60 mg/day to 120 mg/day. This single-arm, non-placebo-controlled study incorporated a 7-week dose escalation phase, in which patients and investigators were blinded as to timing of dose increases, followed by an open-label extension phase of up to 2 years duration. Patients (age >or=18 years) meeting DSM-IV criteria for MDD (n=128) received placebo for 1 week, followed by duloxetine (60 mg/day) titrated after 1 week to 90 mg/day, and after a further week to 120 mg/day. The dose of 120 mg/day was then maintained for 4 weeks. The extension phase comprised an initial 6-week dose stabilization period, during which duloxetine was tapered to the lowest effective dose, followed by continuation therapy at the stabilized dose. We assessed safety using spontaneously reported treatment-emergent adverse events (TEAEs), changes in vital signs, electrocardiograms (ECGs), laboratory analytes, and visual analogue scales (VAS) for gastrointestinal (GI) disturbance. Efficacy measures included the 17-item Hamilton Rating Scale for Depression (HAM-D-17) total score, the Clinical Global Impression of Severity (CGI-S) and Patient Global Impression of Improvement (PGI-I) scales, and VAS assessments of pain severity and interference. The rate of discontinuation due to adverse events during the acute phase of the study was 15.6%. The most frequently reported TEAEs were nausea, headache, dry mouth, dizziness, and decreased appetite. The majority of TEAEs were associated with initial duloxetine dosing; further escalations in dose produced few additional adverse events. VAS measures of GI disturbance worsened significantly compared with baseline values after 1 week of duloxetine treatment. Subsequent assessments of GI disturbance, following dose escalation to 90 mg/day and 120 mg/day, showed either no significant difference or a significant improvement from baseline. Significant improvements (P<.001) were observed in all assessed depression efficacy measures, and in five of six VAS pain outcomes, during acute phase treatment. During 2 years of extension phase therapy, the rate of discontinuation due to adverse events was 11.9%, and the only TEAEs reported by >10% of patients were upper respiratory tract infection (13.1%), headache (10.7%), and insomnia (10.7%). Mean changes from baseline to the end of the extension phase in supine systolic and diastolic blood pressure were 3.8 and 0.5 mm Hg, respectively, and there were no reports of sustained hypertension. Mean increase in heart rate was 5.9 bpm, while patients exhibited a mean weight increase of 3.1 kg over 2 years of treatment. Results from this study suggest that rapid dose escalation of duloxetine (60 mg/day --> 90 mg/day --> 120 mg/day) is safe and tolerable. Despite weekly escalation, the majority of adverse events were mild and transient and occurred in the first week of duloxetine dosing (at 60 mg once daily). Long-term treatment at a stabilized duloxetine dose was associated with a relatively low incidence of TEAEs and treatment discontinuation due to adverse events. Time course profiles of body weight and heart rate showed modest increases during 2 years of treatment [ClinicalTrials.gov number, NC T000 42575].

Trial registration: ClinicalTrials.gov NCT00042575.