A transdermal patch that delivers 20 mcg/hour of the opioid buprenorphine significantly improved pain scores in patients with moderate to severe chronic low back pain, compared with a transdermal dose of 5 mcg/hour or an active control, based on data from 660 patients in a phase III clinical trial.
Transdermal buprenorphine (Butrans) was approved by the Food and Drug Administration in June 2010 for management of chronic pain in adults, said Dr. Deborah Steiner of Purdue Pharma and her colleagues.
In this study, the researchers compared the buprenorphine transdermal system (BTDS), which delivered medication at an average buprenorphine dose of 20 mcg/hour over 7 days, to an average 5-mcg/hour transdermal dose and an active control consisting of 40 mg/day of immediate-release oxycodone capsules. The average age of the patients was 50 years, and the baseline demographics were similar among all three groups.
The findings were published online in the Journal of Pain (doi: 10.1016/j.jpain.2011.06.003).
Patients’ pain was assessed at weeks 4, 8, and 12 using the "average pain over the last 24 hours" scores. In all, 91% of the patients reported musculoskeletal pain as the primary source of their pain at baseline.
At baseline, the mean pain scores in the BTDS 20 group, BTDS 5 group, and oxycodone group were 6.4, 6.5, and 6.5, respectively. After 12 weeks, the mean pain scores in the three groups had dropped to 4.0, 3.3, and 3.3, respectively. The difference of –0.67 between the BTDS 20 and BTDS 5 scores was statistically significant.
"In general, the treatment-emergent adverse effects (TEAEs) observed in this study were similar to those expected with the use of opioid agonists and transdermal patches," the researchers noted. The incidence of TEAEs was 77% in the BTDS 20 group, 59% in the BTDS 5 group, and 73% in the oxycodone group. The most common TEAEs were application-site reactions, nausea, and headaches. The incidence of application-site reactions in the three groups was 29%, 17%, and 22%, respectively; the incidence of nausea was 12%, 8%, and 8%; and the incidence of headache was 11%, 5%, and 10%.
Four separate sensitivity analyses showed that BTDS 20 and oxycodone were significantly more effective for pain control than BTDS 5. In addition, post hoc analyses showed that significantly more patients in the BTDS 20 group than in the BTDS 5 group reported improvements in pain scores of at least 30% from baseline, the researchers said.
The study was sponsored by Purdue Pharma, and most of the study authors are full-time employees of Purdue Pharma.