Source: The Economist Magazine
Contact: http://www.economist.com/

Marijuana as a medicine. A subtle syllogism

Cannabis is a drug. Drugs are supposed to make you better. Therefore
cannabis can make you better. Discuss

"THERE is not a shred of scientific evidence . . . that smoked marijuana is
useful or needed." Thus spake Barry McCaffrey, a retired army general and
Gulfwar hero, in his new role as commanderinchief of the Clinton
administration's War on Drugs. The National Institutes of Health ( NIH )
begs cautiously to differ. An NIH report issued on August 8th said that
eight experts whom it had convened earlier this year expressed "varying
degrees of enthusiasm" about whether the dreaded weed had true medical value
and, if it had, whether it did things that other drugs, less frowned upon by
officialdom, could not. William Beaver of Georgetown University, who chaired
the original workshop, said that "for at least some potential indications
marijuana looks promising enough to recommend that there be new controlled
studies."

Those who advocate marijuana as a medicine usually have four potential uses
in mind: to control glaucoma, to suppress the nausea induced by anticancer
drugs, to relieve the pain of multiple sclerosis, and to stimulate the
appetites of those with AIDS .

Smoking can be good for you

In the case of glaucoma it is widely accepted that the elevated pressure in
the eyeball that damages the optic nerve falls when marijuana is smoked.
That is why, until 1991, America's Food and Drug Administration ( FDA )
permitted ophthalmologists to prescribe the weed to patients for whom other
treatments had failed. Since then, new glaucoma drugs have been produced.
These act at different points in the biochemical pathway that causes eyes to
produce too much fluid. However, no approved drug actually makes the eyes'
drainage system more efficient. If marijuana improves the outflow (which is
possible, but not yet known) it would be a valuable addition to current
therapies.

Marijuana is also of undoubted benefit in suppressing the nausea suffered by
many people on anticancer chemotherapy. The argument here is whether it is
necessary to smoke the stuff for the full benefits to emerge. This is
because a capsule version of marijuana's active ingredient,
delta9tetrahydrocannabinol, or THC , has been passed through the
regulatory process for use in these circumstances.

Despite that, none of the NIH 's experts deemed smoked marijuana to be by
definition a superfluous adjunct to chemotherapy. Unlike oral THC , its
vapour is easily absorbed and acts quickly. It may also contain as yet
unidentified substances that help THC 's action. And, unlike both the THC
capsules and other legal nausea suppressors which work in different ways,
reefers allow users to finetune the dose for themselves. Chemotherapy
powerfully reminds cancer patients of their lifethreatening illness.
Because marijuana cigarettes are under their control, they tend to ease
their feelings of helplessness.

In the case of multiple sclerosis ( MS ), marijuana brings relief that other
painkillers do not seem to manage. Many of those who suffer from this
disease have burning sensations in their limbs, particularly at night. These
sensations are probably caused both by the disorder's destruction of the
protective fatty coating around nerve cells and the damage it does to the
brain.

Conventional analgesics can do little to ease this burning sensation_which
seems to be similar to the phantom pain often suffered by amputees_but some
sufferers say that a joint at bedtime makes the difference between their
sleeping and not doing so. What study there has been of marijuana for MS
_and it is not much_suggests they could be right.

The fourth use_marijuana's wellknown ability to stimulate the appetite_is
particularly significant in the treatment of AIDS . Again, smoking appears
to be better than taking THC in capsule form. The pure form of the drug is
poorly absorbed by many of the afflicted and, besides, often makes people so
high that they never get around to eating. The loss of leanmuscle mass that
occurs as patients waste away to shadows of their former selves is an
ominous predictor of their impending deaths.

The best alternative to smoked pot for appetite stimulation is human growth
hormone, which has been found both to restore lean tissue to emaciated AIDS
patients and to improve their chances of survival. The catch is that_at
$36,000 for a year's supply_it is prohibitively expensive (marijuana
treatment for the same period costs a mere $500). The other readily
available option is megestrol acetate, a synthetic female hormone which is
somewhat cheaper. Unfortunately, studies have shown that it does not improve
survival_probably because the weight gain it produces, instead of being
muscle, is mainly fat.

All this would seem to make smoked marijuana the medicine of choice for
helping the HIV positive to gain the right kind of weight. Indeed, one AIDS
patient testified to the workshop that it had enabled him to regain 40lbs
(around 20kg), and that by using it only at night he had been able to keep
that weight on for four years while working fulltime as a newsletter editor.

Some studies done before the AIDS epidemic found, however, that marijuana
dampens the immune system. Something that depresses their immune systems is
the last thing that AIDS patients need. But these studies were only
preliminary (others came to the opposite conclusion) and they were done
without the benefit of modern techniques for assessing immunesystem damage.
Unfortunately, they have not been repeated_which outlines one of the
greatest difficulties in the effort to assess marijuana's value as a medical
drug: doing trials to find out the truth.

Dont ask, dont tell

A team of AIDS researchers, led by Donald Abrams of the University of
California, San Francisco, planned a patient study aimed at resolving the
immunity issue in 1992, but it was unable to get the marijuana that would
have made the trial possible. The federal government is the only legal
source of the drug for research purposes in America, and scientists cannot
obtain it without the blessing of the NIH . In this case, the NIH stipulated
that the proposal would first have to be given a sufficiently high score by
an independent panel of scientific reviewers. But when the panelists
received it, they refused to review it.

Their reasons for refusing are not entirely clear. Nor is it clear whether,
assuming that such a study were carried out, and that it found marijuana to
be an effective medicine, official approval for its use would then be
forthcoming. America's food and drug law does not say that a drug has to be
better than its competitors for a given purpose to be licensed. It has only
to be better than a placebo. Nonetheless, Robert Temple, an FDA official,
once said that his agency could be forced to withhold approval of smoked
marijuana, despite this aspect of the law. Some drugs are known to induce
paranoia through chemical action. Marijuana, it seems, can do it through
political action instead.