Pubdate: Tue, 11 Sep 2007
Source: Canadian Medical Association Journal (Canada)
Copyright: 2007 Canadian Medical Association
Contact:  http://www.cmaj.ca/
Details: http://www.mapinc.org/media/754
Author: Pauline Comeau, Ottawa
Cited: Canadian Consortium for the Investigation of Cannabinoid 
http://www.ccicnewsletter.com
Bookmark: http://www.mapinc.org/mmjcn.htm (Marijuana - Medicinal - Canada)

NEW DOSAGE LIMITS FOR MEDICAL MARIJUANA

But Where's The Science?

New evidence-based guidelines are urgently needed to help doctors 
negotiate Canada's hazy medical marijuana landscape, particularly in 
light of Health Canada's efforts to impose new dose limits, say the 
nation's leading cannabis researcher and doctors who have been 
queried about their marijuana authorizations.

Canada should also re-establish a formal process for developing 
responsible dosing strategies, says Mark Ware of McGill's University 
Health Centre, the sole researcher funded under the now defunct 
Medical Marijuana Research Program (CMAJ 2006;175:[12]: 1507-8).

The 1053 doctors now authorizing marijuana use for 1816 patients need 
"more evidence" regarding rational dose levels, he says. And Ware 
suggests the Canadian Consortium for the Investigation of Cannabinoid 
could lead such an effort.

"There is more research, more trials, formulations that could be 
done," says Ware. "If we had a couple of days in a room with people 
and pharmacologists then we could sit around and say, here is the 
best we can come up with, here are some guidelines."

Under current medical marijuana rules, doctors authorize the amount 
of marijuana they and their patients feel is necessary. However, 
several who have recommended above 5 g per day were recently 
telephoned by a Health Canada medical marijuana program officer, and 
advised that the department recommends no more than 1-3 g per day, 
irrespective of the medical condition or means of consumption 
(inhaled, ingested or both). Health Canada also posted that 
recommendation on its Web site in October 2006, after officials noted 
the number of authorized users prescribed at more than 5 g per day 
had increased to 15% in June, 2006 from 10% a year earlier.

The lower 1-3-g dose recommendation stems from "an examination of 
current available evidence on daily amounts," stated unnamed 
officials in an email exchange coordinated by Health Canada 
spokesperson, Renee Bergeron. Asked to provide the scientific basis 
for the dose recommendations, the officials cited 3 studies and 
"preliminary Canadian research findings."

In the first study, Medical Cannabis: Rationale Guidelines for Dosing 
(IDrugs 2004;7:464-70), Health Canada selectively noted that users in 
Washington and California consumed 1.42-2.86 g per day. However, the 
study authors go on to recommend a dose range of 0.05-7.40 g per day, 
and that was for a more potent form of cannabis currently produced by 
Health Canada's grower (15% tetrahydrocannabinol content compared to 
12%-plus). Moreover, the study concluded that considering the 
complexity of marijuana dosing, from tolerance to mode of ingestion, 
the guidelines should be viewed only "as a construct to allow the 
physician and patient to develop an individual, self-titration dosing 
paradigm."

The second study surveyed 916 users in the United Kingdom; a third 
documented use among 34 multiple sclerosis patients in Nova Scotia. 
In the latter 2 studies, consumption was less than 1-2 g per day.

Ware authored the UK study and coauthored the Nova Scotia one. In 
both, he says, nothing more than a range of use was documented. He 
notes that marijuana strength and its form of use can alter its 
therapeutic effectiveness.

Susan Russell, acting director for Health Canada's Office of 
Controlled Substances, says ordering patterns under the existing 
medical marijuana program support the 1-3-g limit as does 
"preliminary" Canadian information gleaned from an "unpublished study."

Those preliminary research findings are data from a study by Ware, 
funded by the Medical Marijuana Research program, which is not 
complete. "It is therefore premature to make any public statements 
about the study data; our estimates could yet change with further 
data collection," says Ware.

And while 1-3 g seems reasonable, based on the literature, more 
research is needed to be definitive, he says.

Medicinal marijuana users are frustrated by the latest twist. Tony 
Adams of Victoria, BC, is "furious" about the government's failure to 
respond to his letters regarding dosage reductions. Adams, 60, who 
suffers from degenerative disc disease and severe arthritis, was 
licensed for 7 g per day. He was seeking a boost to 10 g to use as 
tea, but got approval for 5 g.

Health Canada's Russell says the goal of the calls to doctors is 
merely to "verify or clarify the proposed daily amount." But some 
physicians say they have felt challenged, and have either prescribed 
lower doses or withdrawn from the program altogether. "You wonder, 
like with the narcotic control program, if they're going to flag the 
doctors that have high [tetrahydrocannabinol authorization] practices 
or something; if you're going to be under scrutiny," said one 
physician on condition of anonymity.

"In the pain practice, there is enough potential heat on this that I 
do not want to stand out too much," says Dr. David Boyd of Victoria 
Hospital's London Health Sciences Centre, London, Ont. He has 50-plus 
patients using marijuana, and no longer authorizes more than 5 g per day.

University of Ottawa Director of Health Services, Dr. Don Kilby is 
sympathetic to Health Canada's dilemma in managing a program that can 
include people seeking marijuana without true need, and he also sees 
the difficulty doctors face in helping patients whose ailments 
indicate a need for higher marijuana doses. Guidelines are needed, Kilby says.

Russell says Health Canada doesn't plan to develop guidelines, and 
doesn't have any "evidence" that doctors are intimidated by the 
calls. A small, informal survey of doctors is, however, underway.

The CMA received a letter from Health Canada on May 18 indicating 
that the department believes scientific evidence supports lower dose 
recommendations, that some patients receive considerably more and 
that the "apparent discrepancy" is motivating a partial review of the 
Medical Marijuana Access Regulations. Health Canada told CMAJ that 
amendments may be presented for consultation in 2007 or 2008.

CMA Director of the Office of Public Health Dr. Sam Shortt says the 
CMA does not approve of how medicinal marijuana is regulated 
considering the lack of studies correlating outcomes and dosages. 
Shortt advises doctors to read credible studies before authorizing 
marijuana use and to keep detailed clinical notes. The Canadian 
Medical Protective Association recommends physicians ask applicants 
to sign a release from liability. 
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MAP posted-by: Richard Lake