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YES
Crude preparations of herbal cannabis have been used for thousands of years to treat many symptoms, including pain, spasms, and nausea.1 Preparations historically included extracts of roots, leaves, and flowering heads but were not commercially standardized or characterized. Modern pharmacology has identified the principal psychoactive ingredient of cannabis as delta-9-tetrahydrocannabinol; specific cannabinoid receptors have been identified in the central and peripheral nervous system as well as in immune cells, endothelial tissue, and other visceral organs.2 Animal studies have confirmed that many of the effects of cannabis in humanbeings have solid neurophysiologic bases, particularly with respect to pain control.3 The cannabinoid system is, therefore, a major target for drug development.4 History of Medical Cannabis Policy in Canada In 1999 the Court of Appeal for Ontario ruled that it was unconstitutional to enforce the rule of law with respect to cannabis.5 Since 2001, the Marihuana Medical Access Regulations (MMAR) have made cannabis possession legal for authorized patients in Canada. Since July 2005 the streamlined MMAR application requires that physicians sign a form confirming the diagnosis, the symptoms, the fact that prior treatments have been tried or considered, that the use of cannabis has been discussed, and that cannabis is not an approved drug.6 There are 2 main categories of complexes recognized under the MMAR: those requiring approval from family physicians and those requiring approval from both family physicians and specialists. For the second category, family physicians must discuss the case with a specialist; whose name and the date of consultation, but not signature, are required. Amending this process appears to have increased the number of applications. As of September 2006, 1492 persons were authorized to possess medical marijuana and 917 physicians had supported applications under this program.7 Herbal cannabis, cultivated by Prairie Plant Systems Inc under licence to Health Canada, is distributed to authorized patients for $5/g. This herbal cannabis is cultivated under controlled conditions, is free of contaminants, and is irradiated to destroy pathogenic microorganisms. It is delivered as a milled herb with 10 mm particles and moisture content of 15%. The potency is standardized at 12% 2.0% delta-9-tetrahydrocannabinol.8 Cannabis and Family Physicians What do family physicians need to know about the MMAR? First, there is a legal means by which patients can obtain quality-controlled cannabis for medical use. Second, physicians do not "prescribe" cannabis under this approach but instead support a patient's application for authorization to possess the drug. This process reduces the risk of prosecution for patients whose cannabis use is part of a therapeutic approach. Third, medical cannabis use can be documented and monitored as part of standard care. Prescribed cannabinoids offer an alternative to herbal cannabis and should be considered in all cases where cannabis is discussed. Inhaled cannabinoids have the potential pharmacokinetic advantages of bypassing the first-pass effect of hepatic metabolism, of rapid onset of action, and of easy titration. Risks include irritation of the upper airways, cognitive effects of central cannabinoid activity, and stimulation of reward mechanisms. Considerations Advocates for medical marijuana are often involved in political action to change policy. For every placard-carrying marijuana activist, however, many more silent sufferers have turned to cannabis where all else has failed. These patients might be afraid to discuss cannabis with their doctor and might not be aware that they have other legal and safe options. Physicians will formulate their own moral and scientific positions based on available evidence. Cannabis has not yet been formally evaluated in clinical trials, but safety and efficacy studies are under way and further studies should be designed and conducted. Without such trials it is premature to consider prescribing cannabis, but based on what is known of a drug that has been around for thousands of years, based on the safety data generated from 2 generations of recreational users, and based on the mechanism of action of cannabinoids, it is reasonable for family physicians to become more familiar with cannabis. Its undignified position as a drug of abuse with no known medical value deserves to be reconsidered. Dr Ware is Assistant Professor in Anaesthesia and Family Medicine at McGill University in Montreal, Que, Associate Medical Director of the MUHC Pain Centre, and a practising pain physician. Dr Ware receives salary support from the Fonds de la recherche en sante Quebec and holds grants from the Canadian Institutes of Health Research. References 1. Mechoulam R. The pharmacohistory of Cannabis sativa. In: Mechoulam R, editor. Cannabinoids as therapeutic agents. Boca Raton, Fla: CRC Press; 1986. p. 1-19. 2. Pertwee RG, Ross RA. Cannabinoid receptors and their ligands. Prostaglandins Leukot Essent Fatty Acids 2002;66(2-3):101-21. 3. Meng ID, Manning BH, Martin WJ, Fields HL. An analgesia circuit activated by cannabinoids. Nature 1998;395:381-3. 4. Bernadette H. Cannabinoid therapeutics: high hopes for the future. Drug Discov Today 2005;10(7):459-62. 5. Court of Appeals for Ontario. R. v Parker. Toronto, Ont: Court of Appeals for Ontario; 2000. Available from: http://www.ontariocourts.on.ca/decisions/OntarioCourtsSearch_VOpenFile.cfm?serverFilePath=d%3A%5Cusers%5Contario%20courts%5Cwww%5Cdecisions%5C2000%5Cjuly%5Cparker%2Ehtm 6. Marihuana Medical Access Regulations. (2001). Canada Gazette, Part II (reference July 4, 2001-SOR 2001-227). Available from: http://www.hc-sc.gc.ca/dhp-mps/alt_formats/hecs-sesc/pdf/marihuana/marihuana-reg_e.pdf Accessed 2005 Oct 1. 7. Health Canada. Marihuana for Medical Purposes. Statistics (September 1, 2006). Ottawa, Ont: Health Canada; 2005. Available from: www.hc-sc.gc.ca/dhp-mps/marihuana/stat/2006/sept_e.html. Accessed 2006 Oct 28. 8. Health Canada. Health Canada's marihuana supply. Ottawa, Ont: Health Canada; 2005. Available from: http://www.hc-sc.gc.ca/dhp-mps/marihuana/supply-approvis/index_e.html. Accessed 2005 Oct 1. [sidebar] KEY POINTS There is solid scientific rationale for therapeutic use of cannabis. Pharmaceutical cannabinoid preparations should always be considered. Mechanisms exist in Canada for herbal cannabis to to be used legally. Ongoing research and education regarding cannabis is needed. Pubdate: Fri, 01 Dec 2006
Source: Canadian Family Physician (Canada)
Section: Debates
Copyright: 2006 The College of Family Physicians of Canada
Contact: letters.editor@cfpc.ca
Website: http://www.cfpc.ca
Details: http://www.mapinc.org/media/4389
Author: Mark A. Ware, MB BS, MRCP(UK), MSC
Note: Dr Ware is Assistant Professor in Anaesthesia and Family Medicine at McGill University in Montreal, Que, Associate Medical Director of the MUHC Pain Centre, and a practising pain physician. Dr Ware receives salary support from the Fonds de la recherche en sante Quebec and holds grants from the Canadian Institutes of Health Research.
Note: This is the first part of a two part OPED. For the opposing view see http://www.mapinc.org/drugnews/v07.n003.a11.html For the OPEDs in French see
http://www.cfpc.ca/cfp/2006/Dec/vol52-dec-editorial-debates_fr.asp |
