Pubdate: Tue, 09 Mar 2021
Source: New York Times (NY)
Copyright: 2021 The New York Times Company
Author: Jane E. Brody


Dan Shapiro was the first person I knew to use medical marijuana. As a
junior at Vassar College in 1987, he was being treated for Hodgkin's
lymphoma with potent chemotherapy that caused severe nausea and
vomiting. When Dan's mother learned that smoking marijuana could
relieve the distressing side effect, to help her son, this otherwise
law-abiding woman planted a garden full of the illegal weed in her
Connecticut back yard.

Decades later, marijuana as medicine has become a national phenomenon,
widely accepted by the public. Although the chemical-rich plant
botanically known as Cannabis sativa remains a federally controlled
substance, its therapeutic use is now legal in 36 states and the
District of Columbia.

Yet experts in the many specialties in which medical marijuana is said
to be helpful have only rarely been able to demonstrate its purported
benefits in well-designed scientific studies. And they caution that
what is now being legally sold as medicinal marijuana in dispensaries
throughout the country is anything but the safe, pure substance
Americans commonly expect when they are treated with licensed

For example, in Oregon, where both recreational and medicinal
marijuana can be sold legally, all recreational marijuana must be
tested for pesticides and solvents, but such tests are not required
for most medical marijuana, an audit by the Secretary of State
published in January 2019 showed. The Oregon Health Authority does not
require tests for heavy metals and microbes that might sicken users.

Indeed, most of the same health concerns raised decades ago about
using marijuana therapeutically are still unresolved, even as the
potency of the plant's intoxicating ingredient, tetrahydrocannabinol,
best known as THC, has increased fivefold. Furthermore, exclusive
medical use is uncommon; in a Canadian study of 709 medical users,
80.6 percent also reported using marijuana recreationally.

"People are using a medical excuse for their recreational marijuana habit," 
said Dr. Kenneth Finn, a pain management specialist in Colorado Springs and 
editor of a new, 554-page professional book on the subject, "Cannabis in 
Medicine: An Evidence-Based Approach."

Proponents of medical marijuana argue that cannabis is relatively safe
and less expensive than licensed pharmaceuticals and is often used for
conditions for which effective therapies are lacking or inadequate.
Opponents say that what is most lacking are standardized marijuana
products and randomized controlled clinical trials that can clearly
establish benefits and risks.

The evidence - or lack thereof - of health benefits that can be
reliably attributed to smoking, vaping or ingesting marijuana, even in
its purest form, is described in great detail in Dr. Finn's book.
"Components of the cannabis plant can help in various conditions, but
that's not what people are buying in stores," he said in an interview.
"Let's do the research on purified, natural, noncontaminated
cannabinoids," as the various potentially therapeutic chemicals in
marijuana are called.

Three such substances have been approved by the Food and Drug
Administration. One, Epidiolex, a cannabidiol-based liquid medication,
is approved to treat two forms of severe childhood epilepsy. The
others, dronabinol (Marinol, Syndros) and nabilone (Cesamet), are
pills used to curb nausea in cancer patients undergoing chemotherapy
and to stimulate appetite in AIDS patients with wasting syndrome.

Another marijuana-based drug, nabiximols (Sativex), is available in
Canada and several European countries to treat spasticity and nerve
pain in patients with multiple sclerosis.

Medicinal cannabis is hardly a new therapeutic agent. It was widely
used as a patent medicine in the United States during the 19th and
early 20th centuries and was listed in the United States Pharmacopoeia
until passage of the Marijuana Tax Act in 1937 rendered it illegal.

Then a federal law in 1970 made it a Schedule 1 controlled substance,
which greatly restricted access to marijuana for legitimate research.
Also complicating attempts to establish medical usefulness is that
plants like marijuana contain hundreds of active chemicals, the
amounts of which can vary greatly from batch to batch. Unless
researchers can study purified substances in known quantities,
conclusions about benefits and risks are highly unreliable.

That said, as recounted in Dr. Finn's book, here are some conclusions
reached by experts about the role of medical marijuana in their
respective fields:

Pain Management

People using marijuana for pain relief do not reduce their dependence
on opioids. In fact, Dr. Finn said, "patients on narcotics who also
use marijuana for pain still report their pain level to be 10 on a
scale of 1 to 10." Authors of the chapter on pain, Dr. Peter R.
Wilson, pain specialist at the Mayo Clinic in Rochester, Minn., and
Dr. Sanjog Pangarkar of the Greater Los Angeles V.A. Healthcare
Service, concluded, "Cannabis itself does not produce analgesia and
paradoxically might interfere with opioid analgesia." A 2019 study of
450 adults in the Journal of Addiction Medicine found that medical
marijuana not only failed to relieve patients' pain, it increased
their risk of anxiety, depression and substance abuse.

Multiple Sclerosis

Dr. Allen C. Bowling, neurologist at the NeuroHealth Institute in
Englewood, Colo., noted that while marijuana has been extensively
studied as a treatment for multiple sclerosis, the results of
randomized clinical trials have been inconsistent. The trials overall
showed some but limited effectiveness, and in one of the largest and
longest trials, the placebo performed better in treating spasticity,
pain and bladder dysfunction, Dr. Bowling wrote. Most trials used
pharmaceutical-grade cannabis that is not available in


The study suggesting marijuana could reduce the risk of glaucoma dates
back to 1970. Indeed, THC does lower damaging pressure inside the eye,
but as Drs. Finny T. John and Jean R. Hausheer, ophthalmologists at
the University of Oklahoma Health Sciences Center, wrote, "to achieve
therapeutic levels of marijuana in the bloodstream to treat glaucoma,
an individual would need to smoke approximately six to eight times a
day," at which point the person "would likely be physically and
mentally unable to perform tasks requiring attention and focus," like
working and driving. The major eye care medical societies have put
thumbs down on marijuana to treat glaucoma.

Allison Karst, a psychiatric pharmacy specialist at the V.A. Tennessee
Valley Healthcare System, who reviewed the benefits and risks of
medical marijuana, concluded that marijuana can have "a negative
effect on mental health and neurological function," including
worsening symptoms of PTSD and bipolar disorder.

Dr. Karst also cited one study showing that only 17 percent of edible
cannabis products were accurately labeled. In an email she wrote that
the lack of regulation "leads to difficulty extrapolating available
evidence to various products on the consumer market given the
differences in chemical composition and purity." She cautioned the
public to weigh "both potential benefits and risks," to which I would
add caveat emptor - buyer beware.
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MAP posted-by: Matt