by David Wild, Pharmacy Practice News

Montreal—An oral cannabinoid was associated with up to 60% reductions in pain in 10 patients with refractory complex regional pain syndrome (CRPS), according to research presented at the 2010 annual World Congress on Pain in Montreal. The study investigators also reported that most of the patients were able to discontinue long-term opioid therapy and reported significant improvements in quality of life.

The findings support the need for more studies that will examine cannabinoid treatment in the CRPS population, said Mark Ware, MBBS, assistant professor in the Departments of Anesthesia and Family Medicine at McGill University in Montreal, Quebec, Canada.

“Given that few drugs have proven efficacy against CRPS, this study strongly suggests we should take a closer look at cannabinoids for treating this condition,” noted Dr. Ware, who was not involved in the study. “What’s notable here is that even with high doses of nabilone of up to 10 mg/d, patients experienced few adverse events. Although these first reports show doses of this magnitude are safe, clinicians should always start low and go slow when initiating cannabinoid treatment.”

Researchers have become increasingly interested in examining the use of endocannabinoids for various pain conditions, but the efficacy of this class of medications for treating CRPS has not been examined to date. To help fill this gap, investigator May Ong-Lam, MD, clinical assistant professor in the Department of Medicine at St. Paul’s Hospital in Vancouver, Canada, examined data from 10 patients with CRPS who were treated with nabilone (Cesamet, Valeant Pharmaceuticals North America), an oral cannabinoid.

The 10 patients were a mean age of 40 years and had developed CRPS following fractures, soft tissue injuries, invasive procedures or surgeries. Prior to nabilone treatment outset, patients reported moderate to severe allodynia, autonomic changes, burning pain and varying levels of physical disability, despite receiving a range of therapies. These therapies included tricyclic antidepressants, anticonvulsants, selective serotonin or norepenephrine reuptake inhibitors, nonsteroidal anti-inflammatory drugs, g-aminobutyric acid analogues, neuroleptics, ketamine and nerve-blocking procedures.

Nine of the 10 patients also were receiving high-dose opiates, including hydromorphone (10-16 mg/d), transdermal fentanyl (125 mg every three days), oxycodone (30-80 mg/d), morphine (90-240 mg/d), codeine (240 mg/d) and oxycontin (200 mg/d). Without exception, patients rated their pain as 10 on a 10-point visual analog scale (VAS) prior to receiving nabilone

Dr. Ong-Lam initiated treatment with nabilone, a drug approved for the treatment of chemotherapy-related emesis, at a dose of 0.5 to 1.0 mg at bedtime and titrated up until patients reported at least a 50% decrease in VAS scores without experiencing adverse events. Following treatment for three months to two years, patients’ pain scores dropped to between 3 and 6 on the VAS. Moreover, seven of the 10 patients were able to discontinue opioid therapy as well as other pain medications. Among the three patients who continued to receive opioids, cannabinoid treatment corresponded with decreases in pain. This reduced pain was associated with improved sleep, and ability to resume work, bear weight, and conduct daily household chores.

Dr. Ong-Lam emphasized the striking results in this small, retrospective analysis, suggesting that larger studies examining the opiate-sparing effects of cannabinoids in CRPS patients are necessary.

“These patients improved significantly in quality of life and most were able to reduce or discontinue opioids,” Dr. Ong-Lam reiterated. “Furthermore, patients did not develop major adverse reactions or become tolerant of the drug.”

Resource: Pharmacy Practice News