Smoking marijuana effectively relieves nerve pain in HIV patients including aching, painful numbness, and burning, according to a study published in the February 13, 2007 issue of Neurology. The finding is expected to cause a stir again in the ever-lasting debate over the medical value of marijuana.

The study of patients with sensory neuropathy led by Donald Abrams, MD, with San Francisco General Hospital in San Francisco, California and colleagues showed daily nerve pain was reduced by 34 percent in patients who smoked marijuana three joints a day compared to 17 percent in the placebo group.

Sensory neuropathy affects about one third of HIV patients, causing neuropathic pain that is usually perceived as a steady burning and/or "pins and needles" and/or "electric shock" sensations.

The nerve pain is commonly treated with prescription painkillers, but the results are not always satisfying.   Many patients with HIV or cancer reported that smoking marijuana is more effective than the conventional treatment.

However, there has little scientific evidence to support such a claim on the effect of smoking marijuana because researchers have little access to marijuana, which is banned in the U.S. and many other countries and any research can be illegal.

The current study, supported by the University of California Center for Medicinal Cannabis Research involved 50 people with HIV-associated sensory neuropathy, who had an average daily pain score of 30 or higher on a 100-point scale.

In the study, the participants were randomly assigned to smoke either marijuana or a placebo three times a day for five days.  The placebo cigarettes are otherwise identical to marijuana except that a supposedly active ingredient known as elta-9-tetrahydrocannabinol (THC) was extracted.

Those who smoked marijuana were more likely than those who smoked the placebo to experience at least 30 percent reduction in pain, 52 percent versus 24 percent, according to the study.  

The first marijuana seemed particularly effective in relieving the never pain in the HIV patients. It reduced chronic pain by up to 72 percent compared with 15 percent only for placebo.

Dr. Abrams and colleagues reported that adverse events such as sedation, dizziness, and confusion were more common among the cannabis smokers.   But they also said these side effects in both groups were insignificant and they "do not present any serious safety concerns."

“Smoking marijuana was well tolerated and effectively relieved chronic nerve pain from HIV-associated sensory neuropathy,” said Dr. Abrams. “Our findings show the amount of relief from smoking marijuana is comparable to relief provided by oral drugs currently used for chronic nerve pain.”

Better yet, results of the study showed marijuana worked to relieve chronic nerve pain for a wider host of patients than did the anticonvulsant drugs such as lamotrigine and gabapentin, which are prescribed to HIV patients to help ease pain.

According to Abrams, some patients don’t respond well to these drugs. Because of this, there's there’s heightened interest in evaluating marijuana as a treatment for chronic nerve pain.

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

According to the researchers, two placebo-controlled studies were published to show that smoking marijuana can also ease nerve pain associated with multiple sclerosis.

While patients suffering severe pain may be happy about the findings, the federal drug-control agency does not seem enthusiastic about it.   David Murray with the Office of National Drug Control Policy was cited by news media as saying that people who smoke marijuana are subject to bacterial infections. He also said that the study is small and is not convincing enough to consider marijuana as a medical treatment.

But other experts think otherwise.  Igor Grant, director of the University of California Center for Medicinal Cannabis Research was cited by Washington Post as saying the study was probably the best U.S. test of marijuana's medical potential in decades and the results "highly believable."

Dr. Mark Wallace, professor of clinical anesthesiology and program director of the Center for Pain Medicine at the University of California, San Diego, was cited by healthyday.com as applauding the study and saying it was well done.

"There are very few studies of this kind looking at inhaled cannabis and pain, and they are difficult to conduct," he said. "The authors should be commended."

Marijuana use for any purpose is flatly banned by the federal government while some states including California, Alaska, Colorado, Hawaii, Maine, Montana, Nevada, Oregon, Vermont and Washington were reported early to allow patients with severe pain to grow a small number of the plant for personal use.

Angel Raich of Oakland with a brain tumor and Diane Monson of Oroville with degenerative spine disease filed a lawsuit to Supreme Court against the Department of Justice after federal agents seized and confiscated marijuana plants they grew in 2002, which were allowed by the California law.  Raich and Monson followed their physicians' prescription to use marijuana to ease their pain.

The U.S. Supreme Court voted 6-to-3 affirming that medical use of marijuana is a federal crime. The says that the federal government has the power to seize and confiscate any marijuana plant intended for medical use and federal agents can send the violators to jail.

Justice John Paul Stevens who voted along with other justices against the plaintiffs said: "The case is made difficult by respondents' strong arguments that they will suffer irreparable harm because, despite a congressional finding to the contrary, marijuana does have valid therapeutic purposes.

"The question before us, however, is not whether it is wise to enforce the statute in these circumstances; rather, it is whether Congress' power to regulate interstate markets for medicinal substances encompasses the portions of those markets that are supplied with drugs produced and consumed locally."

In the dissenting statement, Justice Sandra Day O'Connor said that the state should have the right to make its own laws. "The states' core police powers have always included authority to define criminal law and to protect the health, safety, and welfare of their citizens," said O'Connor.

Justice O'Connor also said that the court was wrong in, "making it a federal crime to grow small amounts of marijuana in one's own home for one's own medicinal use."

The results of the current study have again ignited hopes in people who support marijuana for medical use.  

"It's time for Washington to stop playing politics with patients' lives and advance this important scientific discovery," healthday.com quoted Steph Sherer, executive director of Americans for Safe Access, as saying in the statement. "The study is a wake-up call for Congress to hold hearings to investigate therapeutic use and encourage research."

Cannabis in painful HIV-associated sensory neuropathy
A randomized placebo-controlled trial
D. I. Abrams, MD, C. A. Jay, MD, S. B. Shade, MPH, H. Vizoso, RN, H. Reda, BA, S. Press, BS, M. E. Kelly, MPH, M. C. Rowbotham, MD and K. L. Petersen, MD
NEUROLOGY 2007;68:515-521