San Francisco, CA:  Cannabis significantly reduces HIV-associated neuropathic pain compared to placebo, and possesses an acceptable margin of safety for use, according to clinical trial data to be published in the journal Neurology.

Investigators at San Francisco General Hospital and the University of California's Pain Clinical Research Center assessed the efficacy of inhaled cannabis on HIV-associated sensory neuropathy in 50 volunteers participating in a five-day double-blind, placebo-controlled trial. Researchers reported that smoking low-grade cannabis (3.56% THC) three times daily reduced patients' pain by 34 percent.

"Thirteen of 25 patients randomized to cannabis cigarettes had >30 percent reduction in pain from baseline to end of treatment versus 6 of 25 patients receiving placebo cigarettes," authors wrote. A 30% reduction in pain is considered to be a clinically significant amount of pain relief.

Investigators added: "Smoking the first cannabis cigarette reduced chronic pain ratings by a median of 72% versus a reduction of 15% with placebo [zero THC] cigarettes. On day five, just prior to smoking the last cigarette, median ratings of current chronic pain intensity were lower in the cannabis group than in the placebo group. Smoking the last cigarette further reduced chronic pain ratings 51% in the cannabis group versus five% in the placebo group."

They concluded: "Smoked cannabis was well tolerated and effectively relieved chronic neuropathic pain from HIV-associated neuropathy [in a manner] similar to oral drugs used for chronic neuropathic pain."

The lead investigator of the study, Donald Abrams of San Francisco General Hospital, initially sought federal approval to assess the potential medical efficacy of cannabis in HIV patients in 1994, but was repeatedly denied access to the US government¹s supply of research-grade marijuana. Today's study is one of the first US-led clinical trials evaluating the efficacy of smoked cannabis to take place in nearly two decades.

The University of California's Center for Medicinal Cannabis Research sponsored the trial. Previous clinical trials assessing the use of cannabinoids as analgesics have demonstrated that  they can significantly reduce the neuropathy associated with multiple sclerosis, diabetes, cancer, and rheumatoid arthritis.

Neuropathic pain affects an estimated one percent of the world's population and is typically unresponsive to both opioids and non-steroidal anti-inflammatory drugs such as ibuprofen.