ALL ABOUT CANNABIS ADMINISTRATION – PART 1
How does one take medical cannabis?
If you imagine someone smoking a joint, you’re not wrong, but that’s not the only method of administration, nor the most recommended.
In the early years of medical cannabis legalization, patients mostly smoked their medical cannabis, as it was the only legal option at the time. Since then, other methods of administration (and associated medical formulations) gained recognition and wider acceptance both from patients and prescribers.
Administration of cannabinoid-based medicines can go through several routes: inhaled (in the lungs), oral (swallowed), oromucosal (through the mouth’s mucosa), transdermal (through the skin), ocular, rectal, etc.
If you want to learn how that works and debunk some myths, tag along in this dive into medical cannabis administration.
CLEARING THE SMOKE ON INHALED ADMINISTRATION
Cannabinoid inhalation produces a fast onset of effects, which can begin within seconds after inhalation; effects peak within 3 to 15 min (depending on authors) and last approximately 2 to 4 hours. [1-3]
With this method of administration, the body absorbs a high proportion of active cannabinoids that can then exert their effects on their site of action. This high bioavailability ranges from 10 to 35%, and sometimes up to 56%. The inhalation method (smoked vs. vapourized) and technique influence bioavailability, where technique may vary on depth of inhalation, puff duration, and breath hold. [1, 2, 4, 5]
Prescribers often consider smoking cannabis as an inadequate method to administer a medication due to the harmful combustion by-products. [6-8] Vapourization appears as a safer, smokeless administration method producing much less harmful by-products than smoking; [3, 9, 10] the latter is possibly less efficient since it could destroy from 30% to 50% of its cannabinoid content.  Vapourization also minimizes throat and lung irritation and can lead to higher cannabinoid blood concentrations as compared to smoking. [3, 6, 11]
BUT WHAT’S VAPOURIZATION?
Cannabis vapourization consists in creating a vapour with cannabinoids (and other desirable elements like terpenes) without burning the plant material.
The current terms used to describe vapourization overlap and makes it somewhat complicated. Two types of vapourization exist:
- dried cannabis vapourization,
- and cannabis extracts/concentrate vapourization (also called “vaping”, or “dabbing” in the case of concentrates).
ARE ALL VAPOURIZERS THE SAME?
Each vapourization method requires a specific type of vapourizer device, which is not necessarily compatible with the other vapourization type. However, those devices fit under the generic name “vapourizer”.
- Dried cannabis vapourizers, also called “dry-herb vapourizer”, use a lower heat (170 to 230˚C) than the one created by burning and smoking cannabis (500-600˚C), and thus creates less harmful by-products. [3, 6]
- Cannabis extract vapourizers, also called vape pens or e-cigarettes, are portable electronic devices that require cartridges (or vape cartridge, vape carts, refill pods, etc.).
- Cannabis concentrate vapourizers can be 2 things: either a “dabbing rig”, a specialized water filtration device with a heating element,  or a compact electronic device (also called dab pen, wax pen) with a small oven to heat concentrates. Depending on the device, cannabis extracts or concentrate vapourizers can operate at higher temperatures (up to around 500˚C). Since concentrates contain very little to no vegetal matter apart from cannabinoids and terpenes, it’s hypothesized that their vapourization at higher temperatures cause less harmful by-products than dried cannabis combustion.
Cannabis concentrates come in a wide selection, such as rosin, live resin, shatter, full-melt hashish, etc.
Some prescribers prefer recommending dried cannabis vapourization over vaping, as Health Canada approved some dried cannabis vapourizers as Class II medical devices (like the Volcano Medic™ and other devices from the brand Storz & Bickel).  Veterans Affairs and some private insurances may reimburse such medical devices.
Vaping of unregulated cannabis products also caused worry in 2019, when Health Canada issued a warning concerning potential pulmonary illness associated with vapourization products (with cartridges).  Vitamin E acetate, an additive present in illegal THC vaping products, is strongly associated with e-cigarette (or vaping) associated lung injury.  Health Canada strictly regulates the manufacturing of medical cannabis vaping products and prohibits potentially harmful solvents.
Note that in Quebec, it is illegal to smoke or vapourize cannabis in a public place without a prescription, whether indoor or outdoor. 
For several patients, smoking or vapourizing cannabis is not the best option. The second most common administration is through the oral route (ingested).
Compared to inhaled administration, which acts fast and for a relatively short period, oral administration takes a while to produce effects and they last longer. Ingested (swallowed) cannabinoid products take effect after a delay of 1 to 3 hours, and the effects last for about 6 to 8 hours, or longer depending on dose, fasted state, and other individual factors. 
The different times of action between inhaled and oral administration are explained by the distinct absorption speeds. Where inhaled cannabinoids go into the lungs and quickly reach blood circulation, ingested cannabinoids get absorbed in the intestine and metabolized (transformed) by the liver, only then reaching blood circulation. This absorption is slow and variable; the bioavailability ranges from as low as 6% and up to 30%. [5, 17]
*A note that the liver converts THC (specifically, delta-9-THC) into an active and potent metabolite (11-Hydroxy-THC), [18, 19] which can contribute to heightened side effects.
Some absorption factors we can’t control, like individual rates of metabolism (some being much faster than others) and sex-related absorption differences; a factor we can control is food intake. [5, 20] Cannabinoids have a high affinity with lipids (fats), and studies found that the absorption of THC and CBD increases (up to 5-fold for CBD) when taken with a high-fat meal. [20, 21]
Oral administration includes several medical cannabis products:
- Oils, made of cannabis extracts and diluted with a carrier oil,
- Capsules, containing a precise dose of cannabis extract diluted with a carrier oil,
- Oral sprays, that deliver tiny drops of cannabis oil,
- Lozenges, sublingual strips, and edibles.
“Edibles” refers to food and beverages that contain cannabis and/or cannabis extracts. While edibles make an appealing administration method for recreational purposes, not all prescribers agree that edibles are an adequate dosing method for medical purposes. Advocates argue that a wider selection of ingested product ameliorate patient access and can better meet their individual needs.
As discussed in our Chronic pain post series, both oral and inhaled administration can serve in some treatment plans:
- Oral administration can serve when a treatment requires day-long pain relief, for example, because of its long-lasting effects  and the accurate dosing of ingested products.  Administration frequency then varies according to pain frequency, from once daily to two or three times a day. 
- Inhalation administration can be helpful to quickly relieve breakthrough pain, [9, 10] with its onset of effects within minutes of inhalation[1-3]. Administration frequency is usually as needed.
However, in some cases a fast onset of effect is needed, but administration through the lungs won’t do because of a medical condition (like chronic obstructive pulmonary disease); in other cases, spot application could be a more direct method of administration, compared to the oral administration that produces effects on the whole body. In such cases, other methods of administration can prove useful.
Stay tuned for Part 2 of this blog post, where we’ll go over oromucosal sprays, topicals, suppositories, and more!
Author: Charlotte Bastin
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
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