Friday, September 5, 2014

Reefer Madness: Hopefully But Probably Not the Last Word

It took at little time but Anonymous has replied to my screed on medical marijuana.  Part of the reason I blogged on this was to initiate reasonable debate on this issue.  In addition in the interests of brevity I did not include a lot of information or arguments.

I have commented on his comments:

 Cannabinoid studies should not be confused with medical marijuana (smoking the whole leaf). How many medications do we smoke? Think about it; If the lungs were the best method then why not nebulize like albuterol.
Not sure whether the lungs are the best method to administer drugs but as I pointed out, since 1846 we have administered general anaesthetics through patients lungs.  I also pointed out that there were objections to smoking including lung damage and risk of fire.  Vapourizers are available, (they are expensive) and I have read that e-cigarettes are being used to smoke marijuana.  Aside from the being safer from the fire point of view, it is questionable whether vapourizing marijuana is any less harmful to the lungs.Further as I pointed out, many patients use extremely small amounts of marijuana.
Also, why include all the other non-useful components of the leaf...we don't do that with opium poppy or any other drug for that matter.
We actually still use opium.   Just about every patient at our site who gets a cystoscopy procedure gets an O and B suppository.  Further opium has been used within my career.  Pantopan which is an extract of opium with the "tar" removed was widely used up until at least the late 1990s.  For all I know it still may be used.  It was the opioid of choice in the burn unit in Vancouver when I was a medical student and on the orthopedic service in Halifax when I was an intern.  It was considered to be superior to morphine or meperidine for bone pain and to have a euphoric effect.  It was still used as a pre-med when I was a resident including by our ultra-paranoid professor.  Some anaesthesiologists, mostly Brits, used it instead of morphine intraoperatively. 

There are reasons why combinations of similar drugs might work better than a single pure drug like perhaps working at different sub-types of receptors or affecting metabolism.  For example in Europe you can get a combination of Morphine and Oxycodone in a single pill. 

In the case of marijuana it appears that a second cannabinoid cannibidiol (CBD) may be synergistic with THC both in analagesic effect and also in reducing side effects.  This is why Sativex has a 1:1 mixture of THC and CDB and why most of the commercially available forms of medical marijuana now specify their THC:CBD ratio.  Now if we have evidence that a second cannabinoid promotes the action of THC, could it be possible that 3rd or 4th cannabinoids might also have a role?
Further, oral cannabinoids exist as treatment (e.g. Marinol).
Marinol is no longer available in Canada.  The manufacturer withdrew it because of low sales.  It was very expensive ($20 per pill) and was not covered under any drug plan.  Nabilone (Cesamet) on the other hand while expensive is covered on our province's drug plan.  I prescribe nabilone widely for a variety of pains. It is a useful drug to try in small amounts in cannabis naive patients.  Some patients who have gotten relief with medical marijuana do get good relief of their symptoms with nabilone.  Many however find that nabilone is not as effective as marijuana or that they get worse side effects.  It has actually been suggested that nabilone may antagonize the effects of medical marijuana by acting as a competitive blocker.

Marijuana does work well orally however because of the bio-availability larger quantities are required, which is a problem with something that was illegal and is now expensive.  It is possible to improve the bio-availability in many ways, including buying this book, or one of the many other ones now available.  You used to be able to download a book on PDF but I guess nothing is free now.  One of my patients practically has a chemistry lab in his kitchen.

Sativex a mixture of THC and CBD from a cloned plant is available in a buccal spray in Canada.  It is unfortunately expensive and not covered under any drug plan, therefore it never caught on although I think it is still a promising product.

So, if you want to promote the use of cannabinoids than more power to you. But you should focus on the pharmacologic properties and appropriate delivery of the drug, like we do with every other drug.
I think I covered this in my previous two posts but apparently not.

Most of us in the pain business would rather we had a pharmaceutical grade cannabis product that we could prescribe to patients either in oral form or as a spray (okay we do have Sativex).  As I mentioned in my previous posts it reflects poorly on the academic pain community and the pharmaceutical industry that with longer than 13 years to work on this we do not have a plethora of products.  In fact with the exception of one evangelical person, nobody in Canada has really done any clinical research on this.  A major factor is of course that it is practically impossible to do any research in cannabinoids in the US which is unfortunately where most of the new drug research for Canada is done.

13 years ago others and I could have stuck our heads up our asses and ignored this issue, like so many people did, but we tried to work with patients to try to get them the best treatment with the limited resources we have.


Anonymous said...

Of course we still use opium, that's the point I was making. We don't use the opium poppy (whole plant). We use the components that matter pharmacologically.

The respiratory hazards of smoking something are related to the byproducts of combustion. Combustion creates smoke and leads to lung cancer. Nebulization does not (not to be confused with vaporizing). Plus, there are several non-medical components of the leaf so why include that in the drug delivery?

You're trying to say there is significant legitimate research proving that the components of marijuana improve pain control and have positive outcomes, but that drug manufacturers don't want to make them? There are far more addicting drugs that have been manufactured for medical use. There are many other options for pain control with similar or better results that do not expose the patient to negative effects like lung cancer.

Bleeding Heart said...

I doubt that nebulization would work for a lipid soluble drug like THC. At any rate someone would have to render the drug down from the plant which would involve the pharmaceutical industry and if you are going to do this, you may as well give it orally or transmucosally.
I suspect Big Pharma has some cannabinoid products "in the pipe" as it were, although I don't seem to see much in the pain literature which suggests we may be several years away. I suspect the prospect of competing with medical marijuana may be scaring them off.