An Open-Label, 52-Week, Phase III Trial of Duloxetine in Japanese Patients with Chronic Low Back Pain

Abstract

Abstract Objective To evaluate the safety and efficacy of duloxetine treatment for 52 weeks. Design Multicenter, open-label, phase III clinical study. Setting Forty-one medical institutions in Japan. Subjects Japanese patients with chronic low back pain (CLBP). Methods Duloxetine 60 mg once-daily was administered for 52 weeks. Safety was evaluated based on adverse events (AEs), vital signs, laboratory test values, electrocardiogram, Columbia-Suicide Severity Rating Scale, and occurrence of falls. The efficacy outcome measures were the Brief Pain Inventory (BPI; average pain, worst pain, least pain, and pain right now), BPI Interference, Patient’s Global Impression of Improvement (PGI-I), Clinical Global Impressions of Severity (CGI-S), Roland-Morris Disability Questionnaire–24 (RDQ-24), 36-Item Short-Form Health Survey (SF-36), and European Quality of Life-5 Dimensions Questionnaire (EQ-5D). Results In total, 151 patients (83 who completed a 14-week placebo-controlled superiority trial and 68 newly registered patients) were enrolled. The incidence rates of AEs and adverse drug reactions (ADRs) were 86.1% and 50.3%, respectively. ADRs with an incidence of ≥5% were somnolence, constipation, nausea, and dry mouth. Treatment discontinuation for AEs occurred in 16 patients. A significant reduction in the BPI average pain score (mean ± SD) was observed at all assessment time points from week 2 (−1.02 ± 1.37) to week 50 (−2.26 ± 1.63), compared with baseline. BPI pain severity (worst pain, least pain, and pain right now), BPI Interference, PGI-I, CGI-S, RDQ-24, SF-36, and EQ-5D showed significant improvement. Conclusion Japanese patients with CLBP had significant pain reduction over 52 weeks without new safety concerns.