The FINANCIAL — According to Lilly, data from a new study suggest that Cymbalta (duloxetine HCl) 60-120 mg once daily significantly reduced chronic low back pain, as measured by the Brief Pain Inventory (BPI) 24-hour average pain score, compared with placebo.
Results from the double-blind, 13-week, placebo-controlled study of 236 patients were presented today at the annual congress of the European Federation of Neurological Societies (EFNS) in Madrid, Spain.
Duloxetine-treated patients reported significantly greater reduction in pain scores than placebo-treated patients. Thirty-one percent of duloxetine-treated patients experienced a 50 percent reduction in pain, compared with 19 percent of placebo-treated patients, as measured by an 11-point Likert pain scale. Physicians consider a pain reduction of at least 30 percent as clinically significant.
Treatment with duloxetine also was associated with improved patient outcomes as measured by the Patient Global Impressions of Improvement (PGI-I), and physical functioning as measured by the Roland Morris Disability Questionnaire (RMDQ-24).
Significantly more patients in the duloxetine group discontinued because of adverse events. In this study, the most common adverse events (those occurring in more than 5 percent of patients in the duloxetine group) were nausea, dry mouth, fatigue, diarrhea, excessive sweating (hyperhidrosis), dizziness and constipation. Adverse events were similar to those seen in previous duloxetine studies in other disease states.
"Chronic low back pain can have a significant impact on a person's ability to do the things they enjoy," said Vladimir Skljarevski, lead study author and a neurologist and medical fellow at Lilly Research Laboratories. "This research may offer hope to those dealing with this debilitating condition."
Study Methods
Adult patients given duloxetine (n=115) and those given placebo (n=121) with a history of non-neuropathic chronic low back pain for more than six months with a weekly mean 24-hour average pain score greater than or equal to 4 at baseline (0-10 scale) and without major depressive disorder were initially treated with duloxetine 60 mg once daily for the first seven weeks in this randomized placebo-controlled trial. After seven weeks of duloxetine treatment, patients reporting less than 30 percent pain reduction (non-responders) had their dose increased to 120 mg once daily. Responders continued on 60 mg once daily. The study's primary objective was the reduction of the BPI 24-hour average pain score. Secondary measures included RMDQ-24, PGI-I, BPI Severity portion (BPI-S) and BPI Interference portion (BPI-I), diary-based weekly mean of the 24-hour average pain score, Clinical Global Impression of Severity (CGI-S), and response rates. Health outcomes, safety and tolerability also were assessed. Continuous efficacy variables were analyzed using analysis-of-variance (ANOVA) with treatment and investigator in the model, or analysis of covariance, with baseline, treatment and investigator in the model, and the stratifying variable of NSAID use (Yes/No). Mixed-model repeated measures (MMRM) analysis also was used to measure improvement at all time points. Treatment groups were compared based on the difference between least-squares means using two-sided testing at the 0.05 significance level. Safety analyses were conducted to compare treatment groups using Fisher's exact test.
Duloxetine data also presented at 12th World Congress of Pain
Data from a separate duloxetine chronic low back pain study were presented on Aug. 21 at the 12th World Congress of Pain in Glasgow, Scotland. At study endpoint, duloxetine did not significantly differ from placebo on the primary measure of weekly mean 24-hour average pain score. However, patients taking duloxetine 60 mg once daily showed significant pain reductions compared with placebo from week three through week 11 of the 13-week trial. This was the first study designed to assess the effect of duloxetine on the reduction of chronic low back pain compared with placebo.
In the 13-week, double-blind, randomized, placebo-controlled study (n=404), patients taking duloxetine 60 mg once daily experienced statistically significant improvements in several secondary outcome measures compared with placebo. Patients taking duloxetine 60 mg once daily also experienced a statistically significant improvement in patient outcomes as measured by the PGI-I and physical functioning as measured by the RMDQ-24. In this study, the most common adverse events (those occurring in more than 5 percent of patients in the duloxetine group) were nausea, insomnia, dry mouth, constipation, headache, diarrhea, dizziness, somnolence (drowsiness) and fatigue.
It is estimated that at least 15 million adults in the United States have chronic low back pain.According to the International Association for the Study of Pain (IASP), pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage. Chronic pain is defined as pain that persists beyond acute pain or beyond the expected time for an injury to heal.(6) Men and women are equally affected by chronic low back pain, and it occurs most often between ages 30 and 50.
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