Inhaled cannabis reduces diabetic neuropathy and the analgesic effect is dose-dependent.
Researchers at University of California San Diego evaluated 16 subjects in a double-blind study to assess the efficacy and tolerability of inhaled cannabis for treating pain caused by diabetic peripheral neuropathy (DPN).
They studied the dose dependent effects of inhaled cannabis on DPN pain and hyperalgesia. Subjects participated in four outpatient treatment sessions, separated by two weeks, where they were exposed to placebo or three different dosages of aerosol 1% THC, the most abundant and psychoactive compound in cannabis. While a drug delivery method for marijuana research, inhalation is preferred because the pharmacokinetics of inhalation are better than smoking, as peak impact occur rapidly and are more easily titrated.
DPN occurs in half of diabetics and 15% have pain, particularly in feet. Numerous patients don't get satisfactory relief from two FDA-approved treatments. Animal research recommends that cannabinoids may be successful in reducing pain, however no studies have concentrated particularly on painful DPN.
"We hypothesized that inhaled cannabis would result in a dose-dependent reduction in spontaneous and evoked pain with a concomitant effect on cognitive function," said lead author Mark S. Wallace, M.D., professor of anesthesiology, University of California San Diego School of Medicine.
Dose-dependent reduction in pain intensity from inhaled cannabis was observed which is consistent with results of other trials of the drug for diverse neuropathic pain syndromes.
"The dose dependent analgesic effect was evident for both spontaneous and evoked pain in the trial subjects, however it was more consistent on spontaneous pain," said Wallace.
All subjects were reported to experience either euphoria or somnolence, which may limit the acceptability of cannabis as an analgesic. However, in measuring the effect of inhaled cannabis impact on cognition (attention and memory), they found modest effects with no dramatic declines or impairments.
"These findings alongside past studies recommend that cannabis may have analgesic benefit in neuropathic pain syndromes, including treatment-refractory DPN," said Wallace.