Pubdate: Tue, 17 Jun 2008
Source: Vancouver Sun (CN BC)
Copyright: 2008 The Vancouver Sun
Author: Pamela Fayerman, Vancouver Sun
Referenced: The CMAJ article
Bookmark: (Marijuana - Medicinal)
Bookmark: (Marijuana - Medicinal - Canada)


Users Experience More Drowsiness, Dizziness Than Non-Users, Research Finds

The use of medical marijuana to relieve pain and other disease 
symptoms can cause a huge range of adverse effects, says an analysis 
of safety studies co-authored by University of B.C. and McGill 
University researchers.

The researchers evaluated 31 studies done around the world during the 
past 40 years and found that while nearly 97 per cent of adverse 
events were not serious or life threatening, medicinal marijuana 
users still have an 86-per-cent increase in the rate of non-serious 
adverse effects like drowsiness and dizziness compared to non-users, 
according to the study in the June 17 Canadian Medical Association Journal.

The risk of suffering serious, adverse effects requiring 
hospitalization is not elevated in medicinal marijuana users, 
compared to non-users, according to the study. But studies on 
patients taking marijuana have nevertheless shown that serious 
effects have rarely been documented, including multiple sclerosis 
relapses, convulsions, respiratory and gastrointestinal disorders, 
urinary infections, cancer tumour progression and psychiatric disorders.

Research on recreational marijuana users who smoke cannabis shows 
they have an increased risk for psychosis and cancer, but the authors 
say no one should assume that the same effects would apply for those 
using it for medicinal purposes, due to different delivery systems and doses.

It's too early to say if medicinal marijuana predisposes patients to 
a higher risk of death or other serious events. In the current study, 
there were 15 deaths among 164 adverse events in 1,932 marijuana 
users but the authors couldn't say whether they were directly related 
to -- or hastened by -- the marijuana products or whether underlying 
diseases caused the deaths.

There were three deaths in 60 adverse events in the control group of 
1,209 non-users but the authors say there is no statistical 
difference between the two groups to show an increased risk of death 
from medicinal marijuana.

They stressed that 99 per cent of the serious adverse events were 
reported in only two major studies, which proves that plenty more 
research needs to be done to make any conclusions about safety issues.

Dr. Jean-Paul Collet, one of the study authors who is a UBC professor 
and pediatrician leading clinical research at B.C. Children's 
Hospital, said in an interview that because of the small numbers of 
cases and patients, it's impossible to say whether the serious 
effects were directly related to the cannabis products.

"There is statistical validity to the non-serious effects like 
nervousness, paranoia, hallucinations, dizziness and anxiety. But it 
would be incorrect to talk about cannabis medicines causing an excess 
risk of death at this point. We cannot make any conclusions about any 
of the serious events. We need more information and more research in 
order to see whether there are any trends," said Collet, who 
previously worked at McGill University when the study was undertaken.

Collet said he wasn't surprised about the non-serious adverse events 
because marijuana is known to impact the central nervous system. The 
study confirms that short-term use of existing medical marijuana 
agents increase the risk of non-serious adverse events, he said. But 
since all the studies analysed were short term (median of two weeks) 
the effects of long term use are poorly understood and high-quality 
trials are needed.

As of a few months ago, 2,432 people in Canada were legally 
registered as medicinal marijuana users. There are four different 
medicinal products available in Canada, more than any other country. 
The products include an herbal extract in a spray form called 
Sativex; some oral (pill form) products called Marinol and Cesamet 
and an herbal plant form, which may be smoked or used as a food ingredient. 
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