By Liz Highleyman

Considerable anecdotal evidence has shown that medical marijuana can help increase appetite, improve wasting, and alleviate treatment-related side effects in people with HIV/AIDS.

Now, a new study reported in the February 13, 2007 issue of Neurology provides the first evidence from a randomized controlled trial demonstrating the therapeutic benefits of medicinal cannabis.

Researchers from the University of California at San Francisco and San Francisco General Hospital (SFGH) undertook a study to determine the effect of smoked cannabis on neuropathic pain due to HIV-associated sensory neuropathy. Peripheral neuropathy may be associated with HIV infection itself, and is a potential side effect of certain antiretroviral drugs including d4T (Zerit) and ddI (Videx).

In this prospective placebo-controlled trial -- conducted between May 2003 and May 2005 -- 50 adults with painful HIV-associated sensory neuropathy were randomly assigned to smoke either cannabis cigarettes containing 3.56% tetrahydrocannabinol (THC) or else similar placebo cigarettes with the cannabinoids removed. Participants smoked cannabis or placebo cigarettes 3 times daily for 5 days. They were asked to stop using marijuana from other sources 2 days before the start of the study, and spent a week at the inpatient General Clinical Research Center at SFGH.

Primary outcome measures included ratings of chronic pain and the percentage of patients achieving at least a 30% reduction in pain intensity. Acute analgesic and anti-hyperalgesic effects of smoked cannabis were assessed using a cutaneous heat stimulation procedure and the heat/capsaicin sensitization model.

Results

• Smoking the first cannabis cigarette reduced chronic pain by a median of 72%, compared with 15% for placebo cigarettes (P < 0.001).

• Over 5 days, smoked cannabis reduced daily pain by a median of 34%, compared to 17% with placebo cigarettes (P = 0.03).

• 52% of the patients who smoked cannabis experienced at least a 30% reduction in pain, compared with 24% of the subjects in the placebo group (P = 0.04).

• Cannabis reduced experimentally-induced hyperalgesia to both brush and von Frey hair stimuli (P </= 0.05), but had little effect on the painfulness of noxious heat stimulation.

• No serious adverse events were reported.

Conclusion

"Smoked cannabis was well tolerated and effectively relieved chronic neuropathic pain from HIV-associated sensory neuropathy," the authors concluded. "The findings are comparable to oral drugs used for chronic neuropathic pain."

"This placebo-controlled clinical trial showed that people with HIV who smoked cannabis had substantially greater pain reduction than those who did not smoke cannabis," said lead study author Donald Abrams, MD. "These results provide evidence that there is a measurable medical benefit to smoking cannabis for these patients."

Given the results of this study, patient advocates with the National Association of People With AIDS and Americans for Safe Access asked Congress to hold hearings on medical cannabis, and to adopt the recommendations of a 1999 report by the Institute of Medicine calling for further study of the drug.

"This study validates what individuals living with HIV/AIDS and their doctors have known for years," said NAPWA's Thomas Kujawski. "People with HIV deserve medications that support the highest quality of life. We call on Congress to put patients before politics and support this research."

Such studies have proven difficult to conduct, since they must be approved by several government agencies including the federal Drug Enforcement Administration and the National Institute on Drug Abuse.

Although several states have laws permitting medical cannabis use for conditions such as HIV/AIDS, cancer, and multiple sclerosis, the federal government maintains that marijuana has no recognized medical uses.

Community Consortium, Positive Health Program, San Francisco General Hospital; Departments of Medicine and Neurology, UCSF Pain Clinical Research Center, University of California San Francisco, San Francisco, CA.

02/16/07

References

D I Abrams, C A Jay, S B Shade, and others. Cannabis in painful HIV-associated sensory neuropathy: A randomized placebo-controlled trial. Neurology 68(7): 515-521. February 13, 2007.

UCSF. Smoked Cannabis Reduced Pain Caused by HIV-Associated Neuropathy. Press release. February 12, 2007.

Americans for Safe Access. New Study of Medical Cannabis Shows Scientific Value for Patients with Neuropathic Pain. Press release. February 12, 2007.

Institute of Medicine. Marijuana and Medicine: Assessing the Science Base. March 1, 1999.