A Pilot Study Shows the Potential of Marijuana as a Treatment for Neuropathy

by Chael Needle

LifeGuide [Treatment Horizons]

In a small pilot study, sixteen HIV-positive participants with neuropathy were given three marijuana cigarettes each day for seven days. Though all of the patients had smoked marijuana before, none had done so in the thirty days prior to the study. Fourteen of the participants were men and had had neuropathy for an average of six years. The results, which were presented at the Eleventh Annual Retrovirus Conference, suggest that marijuana may be an effective treatment for this type of pain.

HIV-related neuropathy has been a challenge for physicians to treat, says lead investigator Donald Abrams, MD, Professor of Clinical Medicine at UCSF, and one of the co-founders and current members of the Positive Health Program, an AIDS services program at San Francisco General Hospital Medical Center. Though some patients have found relief with some anti-seizure medicines, notes Dr. Abrams, HIV-related neuropathy has not been found to respond well to anti-depressants, acupuncture, or opioid analgesics. The idea for the study was bolstered by evidence from animal models that showed that cannabinoids may be useful, particularly in neuropathic pain syndromes, and the fact that Abrams’ research team had established the safety of marijuana in terms of its effect on viral loads and protease-inhibitor interaction. “Marijuana has been reported to have activity as an analgesic, a pain reliever,” he notes. “In [this present] study we not only looked at the effect of marijuana on the patient’s chronic neuropathic pain but we also induced an experimental pain model, with heat and capsaicin (which is the active ingredient in chili peppers). And so while the patients were smoking marijuana, we assessed not only the impact of marijuana in terms of its potential relief of neuropathy, but also of this experimental pain that we induced. The study we reported on at the Retroviral Conference covered only the results of our pilot study, however. The pilot was to see if there was any benefit to smoking marijuana in patients with HIV neuropathy and, if there was, how much benefit in order to figure out what sample size we needed for our follow-up randomized placebo-control trial designed to confirm the results of the pilot study.”

Patients kept pain diaries before, during, and after this trial. But pain was also measured using a visual analog scale: Patients were asked to move a pointer along a line to show how much pain they were feeling. Twelve of the sixteen participants reached the thirty-percent goal in reduction of pain.

Reportedly one-third of those living with HIV/AIDS experience some peripheral neuropathy, or nerve damage. In these individuals, peripheral neuropathy can be caused by HIV itself, some antiretroviral medications (certain NRTIs—ddI, ddC, d4T—are most frequently associated with neuropathy, as well as hydroxyurea, among others), or by opportunistic infections. Heavy alcohol consumption and vitamin deficiency have also been associated with neuropathy. Symptoms can include burning, stiffness, prickling, tingling, and numbness or a loss of feeling in the toes and soles of the feet. The nerves in the fingers, hands, and wrists are also sometimes affected. Nerve damage can heal, but, in extreme cases, it can be permanent.

In this sample, neuropathy was associated with drugs in eight of the participants, with HIV in three, and with both in five. “The majority of them did have dideoxynucleotides contributing to their neuropathy,” says Dr. Abrams. “Some of those patients were continuing on that drug, and some had stopped it years ago.”

If interested in enrolling in the follow-up trial, contact Hector Visozo, RN, at (415) 476-9554, ext. 366 or at hvizoso@php.ucsf.edu.

Chael Needle wrote about six-percent cellulose sulfate gel, a microbicide candidate, in the February issue.