The University of California Center for Medicinal Cannabis Research has supported a study to determine if medicinal use of marijuana provides relief of neuropathic pain. Many patients use “medical marijuana” exactly for this purpose, but to date, the National Institute for Drug Abuse (NIDA), Food and Drug Administration (FDA), and Substance Abuse and Mental Health Services Administration (SAMHSA) have found no studies to support its use.
"This study adds to a growing body of evidence that cannabis may be effective at ameliorating neuropathic pain and may be an alternative for patients who do not respond to or cannot tolerate other drugs," according to lead author Barth Wilsey, MD, from the VA Northern California Health Care System and the University of California, Davis Medical Center. Furthermore, "the clinical utility of cannabis in the United States remains mired in controversy. Akin to the medical and social controversy surrounding the use of opioids in chronic pain, clinical trials will be a critical factor in the debate concerning medical marijuana."
The researchers investigated smoked cannabis in a double-blind crossover study that compared the effects of cannabis to placebo. Thirty eight patients with central and peripheral neuropathy smoked either high dose(7%), or low dose(3.5%) or placebo cannabis, using a standardized procedure. Pain relief was obtained at each dose level, with both concentrations of THC, indicating that pain relief is obtainable with lower doses.
The patients then completed the “pain unpleasantness” rating tool, a validated scale used widely to assist patients with chronic pain. The results showed that “cannabis reduced pain intensity and unpleasantness equally. Thus, as with opioids, cannabis does not rely on a relaxing or tranquilizing effect (eg, anxiolysis) but rather reduces both the core component of nociception and the emotional aspect of the pain experience to an equal degree." Evoked pain remained unchanged, a finding that the authors found surprising, and without “apparent explanation”.
Concerns exist regarding impairments in learning and recall with cannabis use. The higher the dose, the worse the impairment. Dr. Wilsey and colleagues write. "The finding necessitates caution in the prescribing of medical marijuana for neuropathic pain, especially in instances in which learning and memory are integral to a patient's work and lifestyle." To alleviate the ill effects of smoking - another documented concern - alternative methods of use are anticipated, using a recently developed vaporization technique that releases cannanbinoids without the toxins. The authors conclude – “It is reasonable to assume that future clinical trials will utilize this alternative delivery method.”
Further suggestions include combining cannabis with opiates to avoid higher doses of either drug.
References:
Cannabis Cigarettes May Reduce Neuropathic Pain
A randomized, placebo-controlled, crossover trial of cannabis cigarettes in neuropathic pain
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