Medical pot cuts pain, study finds

February 12, 2007

Sabin Russell, San Francisco Chronicle

Doctors at San Francisco General Hospital reported Monday that HIV-infected patients suffering from a painful nerve condition in their hands or feet obtained substantial relief by smoking small amounts of marijuana in a carefully constructed study funded by the state of California.

Although the study was small, it is the first of its kind to measure the therapeutic effects of marijuana smoking while meeting the most rigorous requirements for scientific proof -- a randomized, double-blind placebo-controlled trial.

As such, the results of the trial are being hailed by medical marijuana advocates as the most solid proof to date that smoking the herb can be beneficial to patients who might otherwise require opiates or other powerful painkillers to cope with a condition known as peripheral neuropathy.

The federal government has taken a hard line against marijuana use for medical purposes, maintaining that smoking it is harmful and that there is no scientific evidence to support its legitimacy for treatment in the United States. The U.S. Supreme Court in 2005 ruled that medical marijuana patients can be prosecuted by the government, even in states like California where medical use has been legalized.

"It's time to wake up and smell the data," said Bruce Mirken, spokesman for the Marijuana Policy Project, a group advocating the legalization of the drug for medicinal purposes. "The claim that the government keeps making that marijuana is not a safe or effective medicine doesn't have a leg to stand on."

The study found that most volunteers who were given three marijuana cigarettes a day experienced a significant drop in the searing pain of peripheral neuropathy, which patients liken to a stabbing or burning sensation, usually on the bottoms of their feet. HIV patients are not the only group to experience peripheral neuropathy -- many types of the condition have been identified, and it can also afflict diabetics, cancer patients and people with injuries or infections that affect nerve tissue.

On average, the experiment's participants reported at the start that their pain was roughly at midpoint on a 100-point scale, where zero was no pain at all and 100 was "the worst pain imaginable."

At least half the volunteers who smoked the active marijuana experienced a 72 percent reduction in pain after their first cigarette on the first day of the trial. Over five days, the median reduction in pain reported by the marijuana smokers was 34 percent, compared with 17 percent reported by those who smoked placebo cigarettes that had the active ingredient THC removed in a process akin to decaffeinating coffee.

"This is evidence, using the gold standard for clinical research, that cannabis has some medicinal benefits for a condition that can be severely debilitating," said Dr. Donald Abrams, lead author of the study released Monday by the journal Neurology.

The trial was conducted over a two-year period beginning in May 2003, during which 50 volunteers each spent a week at a secured laboratory at San Francisco General. Patients were required to stop their marijuana use before the start of the experiment. After a two-day orientation period, they were given one cigarette three times a day. Half of the volunteers received marijuana containing about 3.5 percent THC, the active ingredient of the drug. That's significantly weaker than what can be purchased on the street or in medical marijuana dispensaries. The other half received the placebo.

Abrams said that the placebo cigarettes looked and smelled identical to the ones containing active ingredients.

One volunteer, Diana Dodson, a 50-year-old Santa Cruz woman, subsequently learned she had been given the active ingredient. She has tried the FDA-approved pill containing THC, a drug known as Marinol, but said it does not control her pain as well. "For four or five hours, it puts me in a fog," she said.

Smoking marijuana, she said, helps control nausea and her peripheral neuropathy. "I attribute my cannabis use to my staying alive 21 years with HIV," she said.

Dobson described the pain of peripheral neuropathy as a constant sense of burning on the bottoms of her feet, with periodic jabbing pains "like a sharp ice pick, or an electric shock."

After stopping her marijuana use for the required two-day period and then resuming it for the experiment, she said the effect of receiving the real drug again was powerful. "I was a little surprised the results were so dramatic, as they were using low-quality cannabis," she said.

Because of the unusual nature of the experiment, Abrams first had to receive clearance from eight different government agencies, including the University of California, the federal Drug Enforcement Administration and the National Institute on Drug Abuse.

The cigarettes were made from marijuana grown on a federal marijuana farm in Mississippi, and stored in a locked freezer at San Francisco General.

Publication of the paper is a milestone for Abrams, who has been exploring the medicinal effects of marijuana among AIDS patients since 1984 and fought a long battle to win permission from federal agencies to conduct the study.

In the end, it took the taxpayers of California to pay for the research. Under legislation signed by then-Gov. Gray Davis in 1999, the state created the Center for Medicinal Cannabis Research, headquartered at UC San Diego and operating in partnership with UCSF.

Dr. Igor Grant, executive director of the research center, said a total of $8.7 million has been allocated to the program by the state Legislature since it was launched in 2000. Abrams' study, the first of a dozen similar clinical trials now under way, cost $849,000.

Grant said that the findings were "very promising," but stressed that the results of any single trial, no matter how well constructed, are not necessarily definitive. He said that data are now being analyzed from a similar trial that was conducted at UC San Diego. A second trial, also completed at UCSD, enrolled volunteers who were not HIV patients. Their sensitivity to pain was measured using well-established monitoring tests using capsaicin, a cream that stimulates heat-sensing nerves.



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