Buprenorphine Transdermal System for Low Back Pain
Although successful treatment of chronic low back pain can be clinically challenging (http://bit.ly/GBK6Dw), there are several pharmacologic treatment options, including transdermal buprenorphine, that have shown some promise in clinical studies. In “Buprenorphine Transdermal System in Adults with Chronic Low Back Pain” (http://bit.ly/GB8qjN), published in May 2010 in Clinical Therapeutics, researchers evaluated the efficacy and safety of an eight-week course of treatment with transdermal buprenorphine in adult patients with moderate to severe chronic low back pain who had previously been treated with oral opioid analgesics. For the study, patients were randomized to receive 10 mcg/h transdermal buprenorphine or placebo patches, titrated weekly to a maximum dose of 40 mcg/h, for four weeks, and then switched to the alternative treatment for an additional four weeks. Fifty-two patients out of 78 randomized completed at least two weeks of treatment in each study phase. Patients who completed the study phase were eligible to enter a six-month openlabel phase. Primary outcome measure was daily pain intensity, assessed by a 100-point visual analog scale (0 = no pain, 100 = excruciating pain) and a 5-point ordinal scale (0 = no pain, 4 = excruciating). Patients were also assessed using the Pain and Sleep Questionnaire, Pain Disability Index, Quebec Back Pain Disability Scale, and the 36-item Short Form Health Survey. The mean dose of transdermal buprenorphine during the last week of treatment was 29.8 mcg/h (compared to 32.9 mcg/h for placebo).
The researchers reported that treatment with transdermal buprenorphine was associated with significantly lower mean pain intensity scores compared with placebo on both the visual analog scale and the 5-point ordinal scale. Overall Pain and Sleep Questionnaire scores were also significantly lower with transdermal buprenorphine than with placebo. Improvements in pain scores attained during the eight-week treatment phase were maintained in the 27 patients who also completed the sixmonth open-label phase. Compared with placebo, transdermal buprenorphine was more frequently associated with several adverse events, including nausea, vomiting, dizziness, and dry mouth.
In a larger study, “Efficacy and Safety of the Seven-day Buprenorphine Transdermal System in Opioid-naïve Patients with Moderate to Severe Chronic Low Back Pain” (http://bit.ly/GDBzQL), published in December 2011 in Journal of Pain and Symptom Management, patients who responded to and tolerated transdermal buprenorphine (10 or 20 mcg/h) during an initial run-in period were randomized to continue on transdermal buprenorphine (257 patients) or placebo (284 patients) for 12 weeks. Researchers assessed pain intensity in the previous 24 hours using an 11-point scale in patients who completed the 12- week treatment phase. Patients treated with transdermal buprenorphine reported “statistically significantly lower pain scores at Week 12 compared with placebo,” and also did better in terms of sleep disturbance and need for supplemental analgesia. The incidence of reported adverse events was similar for both placebo and transdermal buprenorphine.
The authors of “Efficacy and Safety of Buprenorphine Transdermal System (BTDS) for Chronic Moderate to Severe Low Back Pain” (http://bit.ly/GCXNiy), published in November 2011 in The Journal of Pain, looked at data from 660 patients who had responded to treatment with transdermal buprenorphine and who were randomized to receive either 20 mcg/h, 5 mcg/h, or immediate release oxycodone 40-mg/day during a double-blind 84-day treatment phase. They reported that the primary endpoint of “average pain in the last 24 hours,” assessed during weeks 4, 8, and 12, was “significantly lower” for patients who received 20 mcg/h transdermal buprenorphine compared to those who received 5 mcg/h.
Similar outcomes were also seen in “Buprenorphine Transdermal System for Opioid Therapy in Patients with Chronic Low Back Pain” (http://1.usa.gov/GBGVM0), published in June 2010 in Pain Research & Management. Patients were initiated on 5 mcg/h transdermal buprenorphine, and titrated weekly to 10 mcg/h or 20 mcg/h based on pain relief and tolerability. Patients also received acetaminophen/codeine rescue medication for breakthrough pain. Patients recorded pain intensity in the morning and evening each day using a 100-point visual analog scale and a 5-point ordinal scale. Pain was also assessed during weekly (double-blind phase) and bimonthly (openlabel phase) clinic visits. Patients were also assessed using the Pain Disability Index (pain-related disability), Quebec Back Pain Disability Scale (functional ability), visual analog scales (impact of pain on sleep), and the Short-Form 36 Health Survey (general health status). The group treated with transdermal buprenorphine reported improvements in pain and disability (lower mean daily pain scores, greater decrease from baseline, etc). These reductions in pain intensity were sustained during the six-month open-label phase.
Although further study is needed in larger, more diverse populations, the studies summarized here appear to indicate that transdermal buprenorphine may offer an effective treatment option for patients suffering from chronic low back pain.