AFTER TWO-DECADE HALT, MARIJUANA RESEARCH IS SET

Research on the medical uses of marijuana is scheduled to begin early next
year, for the first time in nearly two decades, now that the government has
approved new experiments to test whether smoking it can help patients who
have multiple sclerosis or who suffer from pain in their limbs as a result
of AIDS.

The new approvals, granted on Nov. 28 by the Drug Enforcement
Administration, do not make it legal for doctors to give their patients
marijuana as treatment; they merely provide for limited use in scientific
experiments. In some states, state law allows doctors to prescribe or
recommend marijuana; federal law prohibits the practice, however, even in
those states.

The D.E.A. approved two experiments when it acted late last month, and
expects to approve a third soon. Officials at the agency said the approvals
did not amount to a policy change, since experiments to discover medical
uses of marijuana had never been prohibited. Rather, said Terry Woodworth,
deputy director for diversionary control, scientists and the public
agencies that finance research have changed their attitudes about the value
of such experiments.

But Paul Armentano, a spokesman for the National Organization for the
Reform of Marijuana Laws, or Norml, said the approvals "have ended a
two-decade-long federal de facto prohibition on medical research on marijuana."

"This is not much yet," Mr. Armentano added, "but it is a recognition by
the federal government that it cannot prevent all work from going forward."

Marijuana experiments require the approval of several federal agencies; the
D.E.A.'s approval is the final one, providing the licensing of the researchers.

The two experiments already given that approval, the third expected to get
it soon and eight others now wending their way through the state and
federal approval pipeline are all scheduled to take place in California and
have been financed by the Center for Medicinal Cannabis Research run by the
University of California.

One of the two studies already approved will concern multiple sclerosis
patients. Some of those patients say they have muscle rigidity that is not
relieved effectively by other drugs, and in any case those drugs have
unwanted side effects. Dr. Jody Corey-Bloom, who will lead this study, at
the University of California at San Diego, cites anecdotal accounts that
marijuana can relieve that muscle pain and rigidity.

In the other approved study, also at the San Diego campus, Dr. Ronald Ellis
will try to determine whether marijuana can relieve a kind of pain in the
hands and feet, known as peripheral neuropathy, that sometimes affects
H.I.V. patients.

Dr. Donald Abrams will also study that condition at the University of
California at San Francisco, in the experiment due for final approval soon.

Dr. Abrams, who has long sought to carry out marijuana studies in AIDS
patients, said that among the most important factors in getting the
research approved were referendums five years ago in which the voters of
California and Arizona made it state law for patients to be allowed to get
marijuana for their illnesses.

After those proposals had passed, scientific committees at the
government-chartered Institute of Medicine and at the National Institutes
of Health reported that there was little evidence that marijuana had
medical usefulness, but that rigorous studies would be worthwhile.

The coming experiments will compare the effects of marijuana cigarettes
with the effects of placebo cigarettes (those with the active ingredients
of marijuana removed).

The marijuana cigarettes will come from a supply grown at the University of
Mississippi under the auspices of the National Institute on Drug Abuse,
said Richard Doblin, president of the Multidisciplinary Association for
Psychedelic Studies, a group that advocates research into the medical uses
of psychoactive drugs. He said one problem with the new research was that
the Mississippi marijuana was very low in potency, a factor that might
hamper the medical effects.

Marinol, an approved prescription drug that has been available for some
years, contains an active ingredient from marijuana plants. But researchers
say natural plants contain many psychoactive agents that are missing from
the commercial product. In addition, Dr. Abrams said, it takes hours for
the full effects of the capsules to be felt, whereas smoking marijuana
produces effects in minutes; the capsule, then, may not be the best way to
deliver the drug.

Experiments using marijuana to stimulate appetite and prevent nausea were
conducted in the United States until the early 1980's. After that, Mr.
Doblin said, disapproving attitudes in the federal government and among
research agencies led scientists to believe that financing of medical
marijuana studies would be difficult to find.

But after the referendums in California and Arizona in 1996, the focus
shifted to the question of whether such medical use could be supported by
scientific evidence.