Pubdate: Sat, 19 Mar 2016
Source: Philadelphia Inquirer, The (PA)
Copyright: 2016 Philadelphia Newspapers Inc
Author: Sam Wood


PA. on Cusp of Legalizing, but Answer Is Complex.

About half the states have legalized marijuana for medical use, and 
Pennsylvania appears ready to join them. Most patients who sign up 
for the drug indicate they're taking it for pain.

But is there evidence that it works?

Simple question, complicated answer. Turns out it works for some 
kinds of pain, but not others, and helps some people more than others.

"The short answer is yes," said David Casarett, director of 
palliative care for Penn Medicine and author of Stoned: A Doctor's 
Case for Medical Marijuana. "But I don't think we really know how it works."

Federal drug authorities long have asserted that marijuana has "no 
currently accepted medical use" and have kept it classified, along 
with heroin and LSD, under the Drug Enforcement Administration's 
most-restricted drug category.

Given the rapidly shifting landscape, the National Institutes of 
Health next week is holding a neuroscience research summit near 
Washington to review the evidence on marijuana and its benefits.

This week, the Pennsylvania House approved a legalization measure, 
and the Senate is expected to follow suit this year. Gov. Wolf has 
promised to sign it when it reaches his desk.

In its current form, the legislation would prohibit smoking 
marijuana, allowing forms such as pills, oils, and ointments. New 
Jersey allows smoking, but adds another limitation: Medical marijuana 
is legal only for pain associated with cancer and HIV.

Pennsylvania's bill allows pot for any pain that cannot be treated 
with prescription painkillers, or pain classified as neuropathic.

Neuropathic pain is complex and common. It can be triggered by 
phantom limb syndrome, diabetes, chemotherapy, multiple sclerosis, 
shingles, and autoimmune diseases such as lupus. It doesn't respond 
well to opioids, the addictive painkillers that also were in the news 
this week, due to new guidelines suggesting how doctors should 
prescribe them. Researchers emphasize that pot is no panacea. 
"Cannabis cannot be used to treat all kinds of pain," said Jahan 
Marcu, scientist at Americans for Safe Access, a nonprofit 
medical-marijuana advocacy group. "It's not going to help you with a 
broken leg."

That's technically known as nociceptive pain, the sharp, throbbing 
ache caused by tissue damage. There isn't good evidence that cannabis 
touches that pain.

But unlike opioids, which have spurred a rising tide of fatal 
overdoses, cannabis-based products are not deadly.

Barth Wilsey, scheduled to speak Wednesday at the NIH summit, has led 
research on marijuana and neuropathic pain as director of the 
University of California Center for Cannabis Research.

"The evidence is moderate," Wilsey said, referring to an analysis 
published in JAMA last year that evaluated 63 studies on THC, the 
most-researched molecular compound in marijuana, for treating pain.

Several of those studies, led by Wilsey and published in the Journal 
of Pain, found low doses of THC significantly reduced neuropathic pain.

In addition, results from a Canadian study published last year in the 
Journal of Pain found medical marijuana was mostly safe for treating 
chronic pain.

Recently in Jerusalem, 176 patients with chronic pain, many of whom 
got little relief from opioids, were given a 20-gram supply of 
marijuana every month for two years. The patients reported a 
"long-term improvement in pain scores" along with a "significant 
reduction in opioid use," according to researchers from the 
Hadassah-Hebrew University Medical Center. The study was published 
last month in the Clinical Journal for Pain.

No large-scale clinical trials have been conducted, in part because 
such trials are generally undertaken by pharmaceutical companies. 
Because marijuana remains a Schedule I drug under DEA rules, no 
company can market it for prescription use, though some prescription 
drugs do contain derivatives from cannabis.

The finding about marijuana's effect on opioid use echoes a 2014 
study at Penn. The study, led by researchers at the Perelman School 
of Medicine, found states that legalized medical marijuana saw a 25 
percent decrease in opioid-related deaths after the law was enacted.

Wilsey said that though medical marijuana may help many people 
suffering from pain, and doesn't carry the risk of fatal overdose, it 
does not come without hazards.

In people with coronary artery disease, consuming it may increase the 
risk of heart attacks "because marijuana races the heart," he said.

An increasing number of studies indicate that in adolescents, pot can 
alter brain development. For some users, mental illnesses may become 
more acute.

"And pregnant women shouldn't touch it," Wilsey said. "There's 
evidence their offspring can suffer with lower academic achievement 
later in life.

"So there are a bunch of conditions."
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MAP posted-by: Jay Bergstrom