Pubdate: Mon, 01 May 2017
Source: Globe and Mail (Canada)
Copyright: 2017 The Globe and Mail Company
Author: Paul Taylor
Page: L3



My mother had a mastectomy after being diagnosed with breast cancer.
It's now six months since her operation and she is still suffering
from sharp, burning pain where her breast was removed. The drugs she
has been given for the pain aren't providing enough relief. I've heard
that marijuana is good for pain. Should she ask her doctor for a
prescription for pot?


It's true that some studies, involving relatively small groups of
patients, suggest marijuana can help ease certain types of pain. But
using marijuana as a medicine isn't necessarily easy because there
aren't yet standardized doses and treatment protocols.

Under the existing federal rules for medical marijuana, doctors are
expected to assess patients and provide them with a document -
essentially a prescription - stating how much marijuana they should
consume per day. The patient is then supposed to get a supply of
marijuana from one of 43 licensed producers who sell their products

Many doctors aren't sure what dose to recommend because of a lack of
guidelines that are based on reliable scientific evidence, says Dr.
Hance Clarke, director of the pain-research unit at the Toronto
General Hospital.

To further complicate matters, not all marijuana is the same.

Clarke points out that most prescription drugs contain a specific dose
of a single active compound.

In contrast, marijuana plants have hundreds of different chemical
compounds, including cannabinoids, which affect a wide range of
processes in the human body.

At least two cannabinoids are thought to have therapeutic benefits -
cannabidiol (CBD) and tetrahydrocannabinol (THC), the ingredient that
makes people feel high.

The amount of CBD and THC varies from one strain of marijuana to the
next. And there's no data regarding the ideal ratio of CBD to THC for
treating pain.

Despite these uncertainties, Clarke says more and more patients are
asking for marijuana, which is increasingly seen as a panacea for
their medical ills. However, some patients have ended up in hospital
emergency departments because they were unprepared for the
mind-altering effects of the drug.

Before they try real cannabis, Clarke says marijuana novices should be
prescribed a low dose of synthetic THC - such as nabilone, a capsule
originally approved for treating severe nausea and vomiting in people
undergoing cancer chemotherapy.

Even with experienced marijuana users, Clarke says physicians need to
provide them with guidance on what to do.

"I don't prescribe anybody marijuana unless they do some homework,"
Clarke says. "They have to look at the websites of the licensed
producers and understand the different strains of marijuana and the
different levels of THC and CBD they contain."

He cautions that patients should be getting marijuana only from
licensed producers - and not storefront dispensaries where the source
of the cannabis may be unknown.

For the best results, patients should closely monitor their reactions
to marijuana and adjust the dose and strain accordingly, Clarke says.

Other physicians, who regularly prescribe marijuana, agree that it's
important for patients to play an active role in determining the most
effective dose for themselves.

"You should start with a low dose and increase it to see if your pain
control is improving," says Dr. Arsenio Avila, an anesthesiologist and
pain specialist at Sunnybrook Health Sciences Centre in Toronto.

He says patients should not expect their pain to be eliminated by
marijuana alone. "It's mostly used in combination with other drugs."

But what's encouraging is that marijuana appears to make it possible
for some patients to get by on lower doses of other pain medications,
including opioids.

Avila notes that patients tend to develop a tolerance to opioids. That
means they need higher and higher doses of an opioid to get the same
level of pain relief. The higher doses, in turn, carry increased risk
of side effects including drowsiness, nausea and severe

"With marijuana, you start to get a better response to your existing
drugs - and you can start to reduce them," Avila says.

What's more, marijuana seems to be especially useful in relieving
neuropathic or nerve pain - an extremely hard-to-treat condition that
sometimes occurs after certain operations, such as mastectomies,
amputations and thoracotomy (chest) surgeries.

For some reason, the nerves in the area of the surgery become altered
or damaged and they lose their ability to transmit normal sensations.
A simple touch on the skin may produce a stabbing, burning or
electric-shock feeling.

Marijuana, working on the central nervous system, may help to dampen
these unpleasant sensations.

Although some of the initial research is promising, much larger
studies are needed to confirm both the benefits and risks of medical
pot, Clarke says.

Ideally, these questions should be answered before cannabis becomes
widely available next year when the federal government plans to
legalize recreational marijuana.

But that's unlikely to happen, Clarke says. There are no financial
incentives for licensed producers to invest in this type of research.
They can easily sell their products in the absence of proper dosing

"I think marijuana has an important role to play in several areas of
medicine," Clarke says. "We just need the science to back it up."

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Paul Taylor is a Patient Navigation Advisor at Sunnybrook Health 
Sciences Centre. He is a former Health Editor of The Globe and Mail. You 
can find him on Twitter  and online at Sunnybrook's Your 
Health Matters.
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MAP posted-by: Matt