Medicines derived from cannabis: A review of adverse events

    MONTREAL, June 16 /CNW Telbec/ - Researchers at the McGill University
Health Centre (MUHC), McGill University and the University of British Columbia
(UBC) determined that medical use of cannabinoids do not cause an increase in
serious adverse events, but are associated with an increase in some
non-serious adverse events.
    Several drugs containing compounds derived from the cannabis plant, or
cannibinoids, are available for medical purposes in Canada. As the use of
cannabinoid medications increases, so do concerns about their potential to
cause "adverse events," or negative side effects. Dr. Mark Ware, Dr. Stan
Shapiro and PhD candidate Tongtong Wang of the Research Institute of the
McGill University Health Centre and McGill University, and Dr. Jean-Paul
Collet of the University of British Columbia examined the nature of these
potential adverse events in a study which will be published June 16 in the
Canadian Medical Association Journal (CMAJ).
    The study was based on the adverse events reported in 31 separate
clinical studies of cannabinoid medications conducted between 1966 and 2007.
Adverse events were categorized as either serious or non-serious; with serious
adverse events defined as those leading to death, hospitalization or
    "Overall, we found an 86% increase in the rate of non-serious adverse
events among the patients treated with cannabinoids compared to the patients
in the control groups," said Ware, a neurosciences researcher at the Research
Institute of the MUHC and assistant professor in anesthesia at McGill's
Faculty of Medicine The majority of events were mild to moderate in severity.
    The majority of non-serious adverse events observed affected the nervous
system, mainly dizziness and drowsiness. "Cannabinoids are used as medicines
because they are neurologically active, so we expected to see some side
effects such as these," said Wang, a PhD candidate in epidemiology and
biostatistics at McGill University.
    Cannabinoids have been shown to treat chronic pain resulting from
diseases such as cancer, multiple sclerosis, arthritis and fibromyalgia, and
also to stimulate appetite and relieve nausea. Physicians must weigh the
possible benefits of treatment against the possible side effects in an overall
attempt to improve the patient's quality of life.
    "We have summarized the adverse events from these studies to help educate
physicians and patients about the possible risks of medical cannabinoids,"
said Collet, formerly at McGill's Department of Epidemiology, and now
professor at University of British Columbia, senior researcher at the Child &
Family Research Institute and Director of the Centre for Applied Health
Research and Evaluation at British Columbia Children's Hospital. "We cannot
extend these results to smoked cannabis or recreational use. That will require
further research."
    This study was funded by a grant from Canadian Institutes of Health
Research, and by a contribution from the Fond de recherche en santé du Québec.

    The Research Institute of the McGill University Health Centre (RI MUHC)
is a world-renowned biomedical and health-care hospital research centre.
Located in Montreal, Quebec, the institute is the research arm of the MUHC,
the university health center affiliated with the Faculty of Medicine at McGill
University. The institute supports over 600 researchers, nearly 1200 graduate
and post-doctoral students and operates more than 300 laboratories devoted to
a broad spectrum of fundamental and clinical research. The Research Institute
operates at the forefront of knowledge, innovation and technology and is
inextricably linked to the clinical programs of the MUHC, ensuring that
patients benefit directly from the latest research-based knowledge.
    The Research Institute of the MUHC is supported in part by the Fonds de
la recherche en santé du Québec.
    For further details visit:

    The University of British Columbia is one of Canada's largest and most
prestigious public research and teaching institutions. It is consistently
ranked among the world's 40 best universities, one of only two Canadian
universities in this category. UBC offers more than 45,000 students a range of
innovative undergraduate, graduate and professional programs in the arts,
sciences, medicine, law, commerce and other faculties. It is ranked within the
top 10 North American universities in the number of U.S. life sciences
patents, including spin-off company creation.

For further information:

For further information: Isabelle Kling, Communications Coordinator
(research), MUHC Public Relations and Communications, (514) 843 1560,; Mark Shainblum, Media Relations Officer
(Research), McGill University, (514) 398-2189,;
Catherine Loiacono, Senior Communications Coordinator, Public Affairs,
University of British Columbia, (604) 209-3048,

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