Medical Marijuana and Chronic Pain

Medical Marijuana and Chronic Pain

As many as one in five Americans lives with chronic pain. Many of these people suffer from neuropathic pain (nerve-related pain) -- a condition that is associated with numerous diseases, including diabetes, cancer, multiple sclerosis, and HIV. In most cases, the use of standard analgesic medications such as opiates and NSAIDS (non-steroidal anti-inflammatory drugs) is ineffective at relieving neuropathic pain.

Survey data indicates that the use of cannabis is common in chronic pain populations, and several recent clinical trials indicate that inhaled marijuana can significantly alleviate neuropathic pain. A pair of clinical trials recently demonstrated that smoking cannabis reduces neuropathic pain in patients with HIV by more than 30 percent compared to placebo.

In 2008 investigators at the University of California at Davis assessed the efficacy of inhaled cannabis on pain intensity among 38 patients with central or peripheral neuropathic pain in a randomized, placebo-controlled, crossover trial. They reported: "[C]annabis reduced pain intensity and unpleasantness equally. Thus, as with opioids, cannabis does not rely on a relaxing or tranquilizing effect, but rather reduces both the core component of nociception (nerve pain) and the emotional aspect of the pain experience to an equal degree."

Preclinical data indicates that cannabinoids, when administered in concert with one another, are more effective at ameliorating neuropathic pain than the use of a single agent. Investigators at the University of Milan reported in 2008 that the administration of single cannabinoids such as THC or CBD produce limited relief compared to the administration of plant extracts containing multiple cannabinoids, terpenes (oils), and flavonoids (pigments).

Researchers concluded: "[T]he use of a standardized extract of Cannabis sativa ... evoked a total relief of thermal hyperalgesia, in an experimental model of neuropathic pain, ... ameliorating the effect of single cannabinoids," investigators concluded. ... "Collectively, these findings strongly support the idea that the combination of cannabinoid and non-cannabinoid compounds, as present in [plant-derived] extracts, provide significant advantages in the relief of neuropathic pain compared with pure cannabinoids alone."

In 2009, an international team of investigators from the United Kingdom, Belgium, and Romania affirmed these preclinical findings in a clinical study of intractable cancer pain patients. They concluded: "[I]n this study, the THC/CBD extract showed a more promising efficacy profile than the THC extract alone. This finding is supported by evidence of additional synergy between THC and CBD. CBD may enhance the analgesic potential of THC by means of potent inverse agonism at CB2 receptors, which may produce anti-inflammatory effects, along with its ability to inhibit immune cell migration. ... These results are very encouraging and merit further study."