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July 24, 2015
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Inhaled cannabis reduces pain in diabetic peripheral neuropathy

Inhaled cannabis can alleviate some of the painful symptoms of diabetic peripheral neuropathy, according to research in The Journal of Pain.

In a randomized, double blind, placebo-controlled crossover study of adults with painful diabetic peripheral neuropathy, researchers found a dose-dependent reduction in both spontaneous and evoked pain with inhaled cannabis, but a more consistent reduction in spontaneous pain.

“This was a single-dose study, and [the] results should be interpreted with caution,” Mark S. Wallace, MD, of the departments of anesthesiology and psychiatry at the University of California, San Diego, told Endocrine Today. “This study used cannabis that was high in tetrahydrocannabinol (THC) and low in cannabidiol (CBD). The study showed that THC can provide pain relief with minimal effects on neurocognitive functioning. However, euphoria and sedation may limit use.”

Mark Wallace

Mark S. Wallace

Wallace and colleagues analyzed data from 16 adults with type 1 or type 2 diabetes and at least a 6-month history of painful diabetic peripheral neuropathy (nine men; eight black; mean age, 57 years). Participants reported peripheral neuropathy pain for an average of 4.8 years, and an average baseline pain intensity of 6.7 out of 10. Researchers performed baseline assessments of spontaneous pain, evoked pain and cognition.

In four sessions separated by 2 weeks, researchers administered aerosolized cannabis in either a low (1% THC), medium (4% THC) or high dose (7% THC) or placebo. Researchers then gauged pain intensity and subjective “highness” scores at 5, 15, 30, 45 and 60 minutes, and then every 30 minutes for an additional 3 hours.

Researchers performed cognitive testing at 5 and 30 minutes, and then every 30 minutes for an addition 3 hours. Linear mixed-effects models were used to compare differences in spontaneous pain over time between doses.

Researchers found a difference in spontaneous pain scores between doses (P < .001). The intensity score for placebo was 0.44, 0.42 and 1.2 points higher than for the low, medium and highest THC doses, respectively. After receiving the highest THC dose, patients reported average pain scores 0.73 and 0.75 points lower than those for the low and medium doses, respectively (P < .001 for both).

Researchers also found that the highest dose of THC had an effect on evoked pain from both a foam brush and a pin prick (P < .001 for both).

Participants exhibited significant impaired performance on two of three neuropsychological tests after receiving a high dose of cannabis, and all participants assigned the high dose reported feelings of euphoria vs. 60% of participants assigned placebo. Some participants also reported drowsiness.

“The sedation from the THC may be beneficial for sleep, as many chronic pain patients suffer from sleep disturbance with very limited options,” Wallace said. “THC may prove a very valuable treatment, and further studies are needed. We also need more studies using CBD, which has no psychoactive effects, but appears to have many medicinal uses.” by Regina Schaffer

Disclosure: The researchers report no relevant financial disclosures.