Updated: Aug 27, 2019
I set out doing research on cannabis for this article 5 weeks ago. I actually started and completed the cannabis training course that has been made mandatory for pharmacists 7 months before the due date. I had gathered inputs from local physicians, and also considered conversations I have had with my patients in the pharmacy. I had further read over several reviews papers and treatment guidelines to synthesize this article.
I want to preface this article by saying that the whole topic of cannabis is very large. As a result I will only be focusing on the evidence behind what cannabis is known to effectively treat. I will also go over the limitations of these evidence, and finally talk about what I believe needs to happen with medical cannabis in order for the product to become more accepted in the medical community.
What is cannabis?
Cannabis is a psychoactive plant that can be smoked, vaporized, or ingested. It is a product that has been used medically or recreationally.
What is THC and CBD?
In the cannabis plant, there are two compounds called Tetrahydrocannabinol (THC) and Cannabidiol (CBD), which are known as cannabinoids. It means that they work on the cannabinoid receptors in the brain and body (National Academy of Sciences, 2017).
Cannabis does contain many other compounds, but with the literature that is available, only THC and CBD has been studied on various medical conditions in a meaningful way (Lafaye, 2017).
THC is a compound that is associated with the euphoric ‘high’ that one gets when taking cannabis, while CBD is a compound that has some effects on the body, but does not contribute to the euphoric high. CBD is believed to balance some of the negative effects of THC, but the extent and nature of its protective effect is unknown.
Pharmaceutically developed ‘cannabinoids’ products.
Prior to medical cannabis being legalized, pharmaceutical companies have created products containing THC and CBD years before. These products are technically classified as “pharmaceutical” cannabinoids because they contain only THC and CBD or contain a very specific amount of THC and CBD. In Canada there are only two of these products, they are known as Cesamet (AKA: Nabilone), and Sativex.
In the current medical literature, how does the world of medicine view cannabis as an actual medicinal product?
Formally with existing literature, medical cannabis that is smoked, inhaled, or ingested has very little to no role in the treatment of virtually all ailments. When the medical literature mentions THC or CBD as a therapy, it typically recommends pharmaceutically developed cannabinoids (Allan et al, 2018).
The following are the only time cannabinoids are to be used:
Neuropathic pain that is resistant to all other medical therapies, Nabilone or Sativex should be considered. Smoked or ingested cannabis are not recommended.
Palliative Cancer Pain that is resistant to other medical therapies, Nabilone should be considered. Smoke or ingested cannabis are not recommended.
Chemotherapy Induced Nausea and Vomiting that is resistant to first or second line medications, Nabilone should be considered. Smoked or ingested cannabis are not recommended.
Spasticity due to multiple sclerosis that is resistant to other forms of therapy, Sativex should be considered. Nabilone may be considered, but it will be considered off label. Smoke or ingested cannabis are not recommended.
Cannabis may weakly help with insomnia and anxiety, but the effect is reserved primarily for pharmaceutical cannabinoids (Nabilone). There are some data that have demonstrated that dried cannabis strains that contain high levels of THC can actually exacerbate anxiety.
CBD ALONE may be considered for VERY specific types of seizures, but only as add-on to existing antiepileptic therapies.
So does medical cannabis even help at all?
On the Government of Canada’s website on medical cannabis, there lists only 13 double blind randomized placebo controlled clinical trials on smoked and ingested medical cannabis that have shown positive results.
These studies showed that cannabis can have an effect on reducing neuropathic pain (Wilsey et al, 2008; Abrams et al, 2007) and musculoskeletal pain (Abrams et al, 2011), improving Crohn's disease symptoms (Naftali, 2013), reducing muscle wasting in patients with HIV (Haney et al, 2005), reducing spasticity due to multiple sclerosis (Corey-Bloom, 2012), and helping (to a small extent) with insomnia (Ware, 2010). So it is known that medical cannabis may have an effect on many different ailments.
The reason why virtually all medical guidelines say “no” to medical cannabis as a treatment is because there is just simply a lack of properly developed clinical studies and a lack of standard methods for which patients can take medical cannabis.
Remember that medications are approved to treat specific conditions when they have been studied many times in a consistent way and have been shown to work. Since cannabis has been illegal in many countries for so long, the number of clinical trials on cannabis is very small. Another problem with studying medical cannabis is derived from the fact that cannabis is primarily smoked or vaporized. Because smoking a joint, or vaporizing cannabis inherently does not have a measured dose, it is virtually impossible to know the exact amount of THC and CBD that was actually absorbed by the participants in these studies. Some participants might have absorbed a lot of THC, while some did not (National Academy of Sciences, 2017).
What is the future of medical cannabis?
Medical cannabis may one day be revealed to be a very important medication, but with what we know about cannabis today, it should not be considered to be a cure-all for any ailments.
I believe that medical cannabis needs to be studied in a much more consistent way in order to move forward. I believe that the biggest factor holding back medical cannabis research is the lack of standardization of cannabis. There are hundreds of different strains, and the content of THC and CBD especially in inhaled cannabis varies widely. Even how the cannabis is inhaled affects the amount of THC and CBD that is absorbed. The only medical cannabis product that has some consistency is cannabis oil which contains a specific ‘mg per ml’ concentration. I can imagine that if cannabis research had to move forward, it would do so with clinical trials based on cannabis oil, rather than smoked or inhaled cannabis. Alternatively, the cannabis industry could also develop a small number of very standardized plants, containing a very specific amount of THC and CBD, to be inhaled in a standardized way, in which case inhaled or smoked cannabis could be consistently studied.
Thank you! As always if you found this article useful, please follow my page, and feel free to share the article if you feel that it will benefit someone else.
Abrams DI, Jay CA, Shade SB, Vizoso H, Reda H, Press S, Kelly ME, Rowbotham MC, Petersen KL. Cannabis in painful HIV-associated sensory neuropathy: A randomized placebo-controlled trial. Neurology 2007 02/13;68(1526-632; 7):515-21.
Abrams DI, Couey P, Shade SB, Kelly ME, Benowitz NL. Cannabinoid-opioid interaction in chronic pain. Clin Pharmacol Ther 2011 12;90(1532-6535; 0009-9236; 6):844-51.
Allan, G.M., Ramji, J., Perry,D. et al (2018). Simplified Guidelines for Prescribing Medical Cannabinoids in Primary Care. Canadian Family Physician. 64, 111-120.
Corey-Bloom J, Wolfson T, Gamst A, Jin S, Marcotte TD, Bentley H, Gouaux B. Smoked cannabis for spasticity in multiple sclerosis: A randomized, placebo-controlled trial. CMAJ 2012 07/10;184(1488-2329; 0820-3946; 10):1143-50.
Haney M, Gunderson EW, Rabkin J, Hart CL, Vosburg SK, Comer SD, Foltin RW. Dronabinol and marijuana in HIV-positive marijuana smokers. caloric intake, mood, and sleep. J Acquir Immune Defic Syndr 2007 08/15;45(1525-4135; 1525-4135; 5):545-54.
Lafaye, G., Karila, L., Blecha, L., & Benyamina, A. (2017). Cannabis, cannabinoids, and health. Dialogues in clinical neuroscience, 19(3), 309–316.
Naftali T, Bar-Lev Schleider L, Dotan I, Lansky EP, Sklerovsky Benjaminov F, Konikoff FM. Cannabis induces a clinical response in patients with crohn's disease: A prospective placebo-controlled study. Clin Gastroenterol Hepatol 2013 Oct;11(10):1276,1280.e1.
National Academies of Sciences, Engineering, and Medicine; Health and Medicine Division; Board on Population Health and Public Health Practice; Committee on the Health Effects of Marijuana: An Evidence Review and Research Agenda. The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research. Washington (DC): National Academies Press (US); 2017 Jan 12. 2, Cannabis. Available from: https://www.ncbi.nlm.nih.gov/books/NBK425762/
National Academies of Sciences, Engineering, and Medicine; Health and Medicine Division; Board on Population Health and Public Health Practice; Committee on the Health Effects of Marijuana: An Evidence Review and Research Agenda. The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research. Washington (DC): National Academies Press (US); 2017 Jan 12. 15, Challenges and Barriers in Conducting Cannabis Research. Available from: https://www.ncbi.nlm.nih.gov/books/NBK425757/
Ware MA, Wang T, Shapiro S, Robinson A, Ducruet T, Huynh T, Gamsa A, Bennett GJ, Collet JP. Smoked cannabis for chronic neuropathic pain: A randomized controlled trial. CMAJ 2010 08/30;182(1488-2329; 0820-3946; 14):E694-701.
Wilsey B, Marcotte T, Tsodikov A, Millman J, Bentley H, Gouaux B, Fishman S. A randomized, placebo-controlled, crossover trial of cannabis cigarettes in neuropathic pain. J.Pain 2008 06;9(1526-5900; 1526-5900; 6):506-21.