WASHINGTONDuring the past 16 years, researchers have developed
data that suggest cannabinoid-based drugs may be effective for a
variety of medical uses, including pain relief, antiemesis, and
appetite stimulation in cancer patients, an Institute of Medicine
(IOM) committee has concluded. It warned, however, that such medical
uses carry some risks, particularly the harmful effects of smoking
marijuana, which it discouraged as a means of delivering medications.
In its report, Marijuana and Medicine: Assessing the Science
Base, the 11-member advisory panel urged rigorous testing of
marijuanas active components, particularly against pain,
nausea, the anorexia of AIDS and cancer, and muscle spasms in
multiple sclerosis. It also called for the development of safer,
fast-acting delivery systems, such as specialized inhalers, so
patients would not have to smoke marijuana.
Currently, Marinol is the only cannabinoid-based drug marketed in the
United States. It is a pill form of THC, the primary psychoactive
ingredient of marijuana, which the FDA has approved for treating
nausea and vomiting associated with chemotherapy and for anorexia and
weight loss in AIDS.
Marijuanas medical effects are generally modest, and for
most symptoms, there are more effective medicines already available
on the market, said John A. Benson, Jr., MD, professor of
medicine and dean emeritus of the Oregon Health Sciences University
School of Medicine. For patients who do not respond well to
other medications, however, short-term marijuana use appears to be
suitable in treating conditions like chemotherapy-induced nausea and
vomiting or the wasting caused by AIDS.
Dr. Benson and Stanley J. Watson, Jr., MD, PhD, co-director of the
University of Michigans Mental Health Research Institute,
served as the panels principal investigators.
Since 1996, seven states have approved referenda that would legally
allow the smoking of marijuana as a medical treatment. However, their
implementation has been thwarted because of threats by the federal
government to yank the narcotics-prescribing powers of physicians who
The IOM report recommended avoiding smoked marijuana whenever
possible because of its health risks. In addition to its common
effect of euphoria, marijuana can adversely affect a users
control over movement and can cause occasional disorientation and
sometimes dependence, although withdrawal symptoms are generally mild
and short-lived, the committee noted. Worse, smoking marijuana
increases a persons risk of cancer, lung damage, and pregnancy
problems, including low birthweight.
Although the panel found marijuana may be useful to treat the muscle
spasms of multiple sclerosis, it found little evidence for using
marijuana to treat other movement disorders such as Parkinsons
or Huntingtons disease.
It also rejected marijuanas usefulness in treating glaucoma,
because smoking it only lowers eye pressure slightly and only for a
short time. Thus, the benefit does not outweigh the long-term risk of
inhaling the drugs smoke.
Although marijuana use often precedes the use of harder drugs, the
panel said no conclusive evidence exists that marijuana is a gateway
drug, one that actually causes people to move up to harder drugs such
as heroin and cocaine. Nor is there evidence that approving the
medical use of marijuana would increase its use among the general
population, particularly if it is regulated as closely as other drugs
with the potential for abuse.
The IOM advisory group took an evidence-based approach to its
assessment, commissioning 14 background papers and 8 technical
commentaries, and had its work reviewed by 13 qualified experts.
Among the panels observations:
The most encouraging clinical data supporting the use of cannabinoids
against chronic pain come from three methodologically sound studies
on cancer pain. In one study, researchers found that the analgesic
effect of 10 mg of THC was equivalent to 60 mg of codeine, and 20 mg
of THC was equivalent to 120 mg of codeine.
Many cannabinoid receptors exist in the nucleus of the solitary
tract, the brain center important to the control of emesis. Most
reports of marijuanas or THCs use against nausea and
vomiting come from chemotherapy-induced emesis, and these indicate
that the degree of efficacy is not high.
In patients with nausea and vomiting, treatment with pills is
generally ineffective because of the difficulty of swallowing or
keeping the drug down. Thus an inhalation (but preferably not
smoking) cannabinoid drug delivery system would be advantageous for
treating chemotherapy-induced nausea.
Cachexia and anorexia are common in end-stage AIDS and metastatic
cancers. However, despite widespread use by AIDS patients, there is
little scientific evidence that marijuana or cannabinoids effectively
counter malnutrition and wasting syndrome.
Oncologists Attitudes Toward Marijuana
Two research teams have surveyed the attitudes of clinical
The studies warrant attention because they are still frequently
There are numerous methodological differences between the two
A 6-week study and a 1-year study both found that participants taking
THC experienced an increase in appetite. But cannabinoids may
modulate the immune system, the report said, which might be a problem
in immunologically compromised patients.
In cancer patients, Marinol has been shown to improve appetite and
promote weight gain.
Finally, a cannabinoid such as THC might prove useful as part of a
combination therapy as an appetite stimulant, antiemetic, analgesic,
and anxiolytic, especially for patients in the late stages of cancer.