Pubdate: Tue, 19 Mar 2013
Source: Canadian Medical Association Journal (Canada)
Copyright: 2013 Canadian Medical Association
Contact:  http://www.cmaj.ca/
Details: http://www.mapinc.org/media/754
Author: John Fletcher

MARIJUANA IS NOT A PRESCRIPTION MEDICINE

What role should doctors play in the control of marijuana? Health 
Canada in a news release late last year announced proposals for "new 
Marihuana for Medical Purposes Regulations," suggesting that "changes 
improve public safety [and] maintain patient access."1 The document 
goes on to suggest that "the proposed new Marihuana for Medical 
Purposes Regulations aim to treat marihuana as much as possible like 
any other narcotic used for medical purposes."1 Under the existing 
regulations it is the federal minister of health who issues a patient 
with authorization to possess marijuana. Under the proposed new 
regulations it is doctors, or possibly other health practitioners, 
who will issue "a medical document, similar to a prescription" 
allowing their patient to obtain marijuana. The language is soothing 
and suggests that marijuana is a medicine, albeit one that needs 
special oversight like morphine and for which users may be seen as 
patients in certain circumstances. It is but a sma! ll step from here 
to suggest that doctors should prescribe marijuana for medical 
indications. But is marijuana a medicine? Or, more specifically, is 
it a prescription medicine?

Marijuana is certainly pharmacologically active, but that is also 
true of a large number of compounds that are not medicines, such as 
dry cleaning fluid. Marijuana may be used to relieve pain and appears 
to be effective in this role for some people.2 Hence, it is a drug, 
but then so are many other plants that are not used as prescription 
medicines such as St John's wort or belladonna. What characterizes a 
prescription medicine is that it has an identifiable compound or 
active ingredient that has a known potency in its pure form; its 
pharmacokinetics and route of delivery are understood; it is 
delivered safely; it is manufactured with a consistent formulation; 
and it has undergone regulatory studies and been approved as having a 
favourable balance of benefits and harms. Several prescription 
medicines have already been developed from cannabis,1 but under the 
proposed new regulations marijuana itself has none of the above 
characteristics. Doctors are being asked to prescribe a ! dried leaf 
containing several compounds of unspecified potency, some of them 
active and none of them pure; smoking is an unreliable way to deliver 
a consistent dose, is probably harmful and no other medicine is 
administered this way; there is no evidence that those offering to 
supply marijuana understand how to deliver a consistent drug dose in 
a smoked product; and, most important, marijuana has not undergone 
regulatory testing and approval as a medicine.

Marijuana is a drug that is at a similar stage of development to 
poppy and foxglove in the 19th century. Although doctors may have 
prescribed those drugs then, in the 21st century we prescribe 
morphine and digoxin. If the government is serious about asking 
doctors to prescribe marijuana, it should remove the barriers to 
developing marijuana as a pharmaceutical product. Then doctors would 
have a medicine they could prescribe with some knowledge as to its 
effectiveness and side-effect profile, safe in the knowledge that 
they are not alone in the firing line should something go wrong. But 
there is no suggestion in the recent announcement that this is the 
government's intention.

The real impetus for change is probably to control the use of this 
illegal substance and to reduce the risk of fire from home growing 
operations. In her announcement of the proposed new regulations, 
Minister of Health Leona Aglukkaq said "Current medical marihuana 
regulations have left the system open to abuse. We have heard real 
concerns from law enforcement, fire officials and municipalities 
about how people are hiding behind these rules to conduct illegal 
activity and putting health and safety of Canadians at risk."1 These 
are real concerns. The number of people authorized to use marijuana 
has grown faster than was expected from 500 in 2002 to 26 000 today,1 
and it is clearly hazardous to grow a regular supply of this 
flammable resinous plant at home in a basement. But it is muddled 
thinking to suggest that the solution is for doctors to prescribe it.

It does make sense for doctors to be involved, though. We are at an 
awkward stage in marijuana's development because it is a potentially 
useful, but illegal, herbal product that the government is prepared 
to tolerate in certain circumstances. It would be much better for the 
government to specify criteria that must be met for an individual to 
be permitted to use marijuana. The doctor's role would then be to 
certify that a patient met these criteria. This is not the same as a 
doctor making a diagnosis and deciding to prescribe a drug for a 
defined indication. This is more akin to certifying that a patient 
meets the government's criteria for a disabled parking permit. The 
doctor does not suggest the patient should drive or that a disabled 
parking place would be good for them, just that they do fall into the 
category of person that the government says may have one.

It is time the government made up its mind. Does it want marijuana to 
become a medicine? If it does, it should work with the pharmaceutical 
companies to ensure that this is a properly researched and developed 
drug. At the moment, marijuana is a herbal product and not a 
medicine. Doctors should not allow themselves to be lulled into prescribing it.

References

1. Harper government announces proposed new marihuana for medical 
purposes regulations - changes improve public safety, maintain 
patient access. Ottawa (ON): Health Canada; 2012. Available: 
www.hc-sc.gc.ca/ahc-asc/media/nr-cp/_2012/2012-193bkc-eng.php 
(accessed 2013 Feb. 14).

2. Ware MA, Wang T, Shapiro S, et al. Smoked cannabis for chronic 
neuropathic pain: a randomized controlled trial. CMAJ 
2010;182:E694-701. Competing interests: See 
www.cmaj.ca/site/misc/cmaj_staff.xhtml Afiliation:John Fletcher is 
Editor-in-Chief, CMAJ. Correspondence to:CMAJ editor,  
CMAJ 2013. DOI:10.1503/cmaj.130267
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