Last month,when a report commissioned by the White House concluded that smoked marijuana may have some legitimate medicinal uses, big-city newspapers were quick to highlight that particular facet of the study: Chicago Tribune ("Marijuana Can Be Medically Useful"), San Francisco Chronicle ("Pot Has Medical Value"), Los Angeles Times ("Pot Has Uses As Medicine"), The New York Times ("Government Study of Marijuana Sees Medical Benefits"), and the Pittsburgh Post-Gazette ("Medical Study a Score for Pot").
But lost in the haze was what the study really found: Marijuana has very limited potential as a valid drug therapy.
"Marijuana's medical effects are generally modest, and for most symptoms there are more effective medicines already available on the market," said the study's co-principal investigator John Benson Jr., at a press conference convened upon release of the report. "While we see a future in the development of chemically defined cannabinoid drugs," said Benson, "we see little future in smoked marijuana as a medicine."
Co-principal investigator Stanley Watson concurred: "Marijuana's future as a medicine does not involve smoking."
The Institute of Medicine (IOM), a nonprofit arm of the National Academy of Sciences, produced the report for the Office of National Drug Control Policy. It was heavily weighted with data validating the quality of current drug therapies for conditions pot advocates say smoked marijuana helps-like AIDS wasting and chemotherapy-related nausea.
For example, powerful new anti-nausea drugs, or antiemetics, have emerged over the past decade. These have dramatically reduced the nausea and vomiting associated with cancer chemotherapy and, according to the report, have literally transformed patient tolerance of certain difficult cancer treatments. Some newer antiemetics have helped 75 to 90 percent of cancer patients achieve complete control of nausea. "Cannabinoids are not as effective as several other classes of agents," the IOM report stated.
In the case of AIDS wasting (the deterioration and loss of body mass), researchers are still looking for the right product. They reported that the drug megestrol acetate increases food intake by about 30 percent, but produces weight gain that is fat tissue instead of the desired lean body mass. Newer therapies include "enteral nutrition," or introducing nutrients directly to the intestines. But again, this procedure produces mostly fat.
The IOM report concluded that although cannabinoids might prove useful as an adjunct therapy for AIDS wasting, they are not likely to be primary weapons. The reason? As with megestrol acetate and enteral nutrition, increasing food intake, the goal cited by medical marijuana advocates, would most likely be ineffective in increasing lean body mass, the goal of any such therapy.
"Despite the IOM's exhaustive review, they did not find a sufficient amount of scientific information that [marijuana] is more effective than any drugs already in use," said Jim O'Brien, a pharmacologist and internist at the University of Connecticut Health Center in Farmington, Conn. "Maybe new classes of cannabinoid drugs can be developed, but that remains to be seen."
Currently, the only cannabinoid-based drug on the market is Marinol. The drug delivers THC, marijuana's psychoactive component, in pill form. Marinol is approved by the FDA for nausea and vomiting associated with chemotherapy, as well as for anorexia and weight loss associated with AIDS. Many physicians report success with the drug, but some patients and doctors complain that, when used to combat nausea, Marinol doesn't act quickly enough. Doctors are also concerned about pinpointing proper dosing levels. Unimed, the drug's manufacturer, is currently developing improved delivery methods, including an inhalant.
Meanwhile, says Mr. O'Brien, the problems with Marinol aren't going to be solved by smoking pot-especially not the dosing problems. THC levels in marijuana distributed through medical "marijuana clubs" vary wildly, he says, because of differences in plant-growing conditions like light, air, and soil quality. And the presence of harmful fungi can make pot plants just plain toxic. "From a scientific standpoint, it's a disaster," Mr. O'Brien said.
According to the IOM report, laboratory-produced drugs are preferable to plant products because they are made under controlled conditions and deliver a consistent dose. Currently, three such drugs-HU-211, CT-3, and THC-are in varying phases of development by drug companies.
But they'll take a while. Meanwhile, marijuana advocates-such as the libertarian Orange County Register editorial page-lambaste policies to suppress medical pot-smoking as "based on myths, fears, and outright falsehoods." So what would be false and mythical? To sidestep science and authorize widespread use of a multi-constituent drug with significant known adverse effects? Or to explore carefully the use of cannabinoids to ensure that seriously ill patients aren't further jeopardized with a drug whose worst side effects may yet be unknown?