Inhalation: Smoking vs Vaping
Smoked cannabis refers to direct combustion of the cannabis plant and inhalation of the smoke from combustion. Vaporization is a method of inhaling cannabis vaporized by heat without flame which decreases the number of toxic byproducts produced by combustion.
Links to other Pertinent Educational Pages:
Use and Dosing:
- Inhalation: Smoking vs Vaping
- Marijuana – Flower vs Pharmaceutical Products
- Oral Use (Edibles)
- Dosing: “Pot” vs Pharmaceutical Products
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Inhalation: Smoking vs Vaping
There are a number of differences between smoking and vaping marijuana (cannabis). Although smoking raw marijuana has the advantage of being less expensive, with further evaluation vaping is generally recommended over smoking.
Smoking flowers by combustion (burning) is associated with greater health risks including chronic bronchitis as opposed to vaping, the preferred method of inhalation. Additionally, vaping provides a more efficient means of extracting THC and other constituents from the flower. For example, the bioavailability of cannabis is:
- Smoking: 25-30% bioavailability (Reports vary from 2-56%)
- Vaporization: 30-60% bioavailability
This means that one may access as much as twice as much of a flowers active constituents by vaping rather than smoking.
- Most common route of administration, but not recommended (joints, bongs, pipes, etc.)
- Combustion heats cannabis to 600–900 °C (1100-1650 °F) produces toxic biproducts including: tar, PAH (polycyclic aromatic hydrocarbons, or “tars”), carbon monoxide (CO), nitrosamines and ammonia (NH3).
- Chronic smoking is associated with respiratory symptoms (bronchitis, cough, phlegm), but not lung cancer nor COPD (if cannabis only). Bronchitis associated with smoking cannabis resolves after cessation of use. Mixing cannabis with tobacco increases respiratory/cancer risk
- 30–50% of cannabis is lost to ‘side-stream’ smoke. A 2003 nnalysis of vapor from a vaporizer recovered 89.1% THC and 9.5% smoke toxins; in contrast, cannabis smoke from a pipe recovered 10.8% THC and about 87% smoke toxins.
- Cannabis (and tobacco) smoking induce the liver enzyme CYP1A2, and this induction is additive when they are smoked together. This may be significant in a patient taking a medicine metabolized by CYP1A2 such as tizanidine (Zanaflex). In this case it is the smoke itself that is responsible for the induction, not the drugs.
- Vaping heats cannabis to 320–450 °F (160–230 °C) This reduces carbon monoxide (CO) exposure but does not completely eliminate exposure to PAH (polycyclic aromatic hydrocarbons).
- Vaporization produces significantly less other harmful byproducts vs. smoking.
- Reduced pulmonary symptoms are reported compared to smoking.
- As a rule of thumb, loading 0.3 gm of flower rated at 18% THC would allow for a maximum delivery of up to approximately 50 mg THC, less 30–50% of cannabis lost to ‘side-stream’ smoke, equating to a THC dose of about 25-30 mg THC.
- Oven-style Vaporizers for marijuana flower (available, but not sold in LA pharmacies) Vaporizers designed for use with loose marijuana flower have a small “oven” chamber that allows for loading up to 0.3 gms of flower to be vaped. The vaporizer heats the flower to 360 – 420 F over about 45 seconds until it is ready for inhalation.
There are multiple brands and models available in vape shops and on the internet but they are not sold in LA marijuana pharmacies. One popular oven-style vaporizer is the Pax 2 which sells for $150.
Vaporizers should provide the option of setting a vape temperature. The reason for this is that different cannabinoids and terpenes vaporize at different temperatures. If the flower is not heated to a temperature sufficient to vaporize the particular constituents in the flower, these constituents won’t be able to be inhaled and their benefits will be lost.
In general, cannabinoids vaporize at temperatures from 315• – 430• F (157• – 220• C) while terpenes vaporize at temperatures from 150• – 390• F (66• – 198• C). While it may be best to set the temperature as low as possible to avoid irritation of the airways, the temperature should be set 10• – 15• F) above the vaporizing point (VP), or boiling point, of the desired constituent with the highest VP. With each flower listed below, the minimum VP is identified based on the terpene profile (when known).
One can also modify the effects of vaping flower by adjusting the temperature directed at modulating the THC which vaporizes at 315• F. By vaping at, or just above this temperature, less THC will be released allowing for a more subtle effect compared with higher settings which will create a greater burst of vaporized THC. And, depending on the terpene profile of the strain, one can also modify the experience by modulating the terpene vaaporization.
For example, the terpene pinene (which promotes alertness) is vaporized at 311• F, so keeping the temperature around 315• – 320• allows for a more subtle THC experience with the addition of the uplifting pinene effects, while at the same time by keeping the temperature below 330• F it will avoid the sedating effects of any myrcene present since it needs 330• F to vaporize.
One should be aware that β-caryophyllene, arguably the most important terpene for pain benefits, vaporizes at a significantly lower temperature (266• F) and would therefore be available at the temperatures discussed above.
Some cannabinoids have higher vaporization temperatures, including cannabichromene (CBC – 428• F), cannabinol (CBN – 365• F) and THCV (428• F). Of note, CBD doesn’t have a clear set VP, it is more of a vaporization range from 320-356• F (160-180°C), slightly higher than THC.
Therefore, to be certain to get the benefit of the full complement of cannabinoids and a more rapid vaporization of THC and CBD for the strongest impact, higher vaporizing temperatures should be used (430-450• F).
While vaporization points are meaningful, they are not absolute. The vape chamber of the device may not heat the chamber contents perfectly evenly, creating hot and cold spots in the flower that will affect over-all vaporization. An additional factor is that, to a small degree, these constituents may sublimate off at a lower temperature.
The minimum vaporizing temperatures listed with each flower is the temperature at which all significant constitutent cannabinoids and terpenes will vaporize.
- Smoking/Vaping onset of maximum effect: 5–10 minutes
- Smoking/Vaping duration of effect: 2-4 hours
- Rapid action, advantage for acute or episodic symptoms (nausea/pain).
Oral Ingestion vs Inhalation
- Juicing cannabis or making cannabis teas from plant marijuana do not allow for adequate decarboxylation of THCA and CBDA, the relatively inactive components rhat are found in the raw plant that require heat to be converted to the more active forms, THC and CBD.
- Oils, capsules and other oral routes have become increasingly popular due to convenience and accuracy of dosing.
- Edibles (brownies/cookies) are often more difficult to dose and lead to accidental ingestions, especially children. There are a growing number of reports of accidental overdosing with edidles leading to extreme side effects including panic attacks, paranoia and psychotic-like symptoms. See: Oral Use (Edibles)
- Tinctures and lozenges designed to be held in the mouth or under the tongue to allow for more rapid absorption into the blood through the oral mucosa have intermediate onset between inhaled and oral but have limited research. See: Tinctures
- Oral onset of maximum effect: 60-180 minutes
- Oral duration: 6-8 hours
- Less odor, convenient and discrete, advantageous for chronic disease/ symptoms but titrating dosing is more difficult.
Oromucosal (Sublingual & Buccal)
- Oromucosal onset of maximum effect: 15–45 minutes
- Oromucosal duration of effect: 6-8 hours
- Do not operate dangerous equipment or perform potentially dangerous activities after use
- Do not combine with tobacco
- Do not use with alcohol, opioids, or sedating drugs
- Keep cannabis safely stored under lock and key
- The maximum recommended dose is 1 inhalation 4 times per day (approximately 400 mg per day) of dried cannabis containing up to 9% THC.
Cannabis users should be advised not to drive for at least:
- Three to four (3 to 4) hours after smoking
- Six (6) hours after oral ingestion
- Eight (8) hours if they experience a subjective “high”
Cautions Associated with Inhalation
Inhaled cannabis should be used with caution in:
- Patients who smoke tobacco
- Patients who are at increased risk of cardiovascular disease
- Patients who have anxiety or mood disorders
- Patients who are taking high doses of opioids or benzodiazepines
The principle reason for caution with inhaled drugs is that in general inhaled drugs have more immediate and higher blood levels associated with this means of administration. Therefore, especially in the case of cannabis-based products, there is a greater risk for side effects, especially cognitive dysfunction such as sedation, confusion and impaired decision making and problem solving. Also, with inhaled medications there is greater difficulty in accurately determining dosage unless provided with inhaler devices designed to deliver specific amounts of drug. Additionally, due to the heightened and immediacy of drug-induced effect associated with inhalation, there is an increased risk for abuse and addiction compared with other means of administration such as sublingual, buccal or oral.
Dosing Considerations with Raw Marijuana
- The determination of dosing is one of the major stumbling blocks in the study of medical marijuana. This is because marijuana, a plant, varies widely in the amount and ratios of the pharmacologically active constituents present depending on a multitude of variables. Depending on the plant there may be over 100 pharmacologically active constituents all of which vary depending on the genetics of the plant, the conditions in which the plant was grown, how and when it was harvested and other variables. As such there is a huge variability in the potency and expected effects between different plants.
- As noted above, the major pharmacologically active constituents found in marijuana are the cannabinoids THC and cannabidiol (CBD). The average contents of THC and CBD in dried plant preparations of marijuana confiscated from 1993 to 2008 in the United States were 4.5 and 0.4, respectively, although these contents vary widely. In the last decade these percentages have increased in different strains to more than 5-10 times as potent.
- In addition to the cannabinoids there are other constituents found in marijuana that may contribute significantly to the pharmacologic effects. Include in these other constituents are the terpenes, fragrant chemicals that often give the notable scents associated with marijuana leaves and flowers. Their pharmacologic roles are currently being studied.
- It is also believed there may be an “entourage” effect in which the synergistic actions of the many pharmacologic agents in marijuana contribute to the overall effects, both therapeutic and adverse. Thus it may not be the amount of THC and/or CBD that singularly determine the pharmacologic effects but the overall combination and ratios of the many pharmacologic constituents present in the plants.
The Canadian Experience
In Canada, the medical indications for inhaled marijuana (dried plant) are limited to those patients with severe neuropathic (nerve) pain who have experienced inadequate pain relief or intolerable side effects with trials of standard treatments including: NSAIDs, anticonvulsants (gabapentin (Neurontin) or pregabalin (Lyrica), antidepressants (duloxetine/Cymbalta) and amitriptyline/Elavil, or opioids (tramadol, hydrocodone etc.) and have not responded to adequate trials of pharmaceutical cannabinoids.
Canadian Guidelines Contraindicating Use of Inhaled Cannabis Products:
Inhaled cannabis is contraindicated in:
- Patients who are 25 years of age or younger
- Patients who have a current, past, or strong family history of psychosis
- Patients who have a current or past cannabis use disorder (marijuana addiction)
- Patients who have a current substance use disorder (chemical or behavioral)
- Patients who have cardiovascular or respiratory disease
- Patients who are pregnant or planning to become pregnant
Canadian Dosing Guidelines – Inhaled Cannabis (Smoked and Vaped)
Based on these Canadian guidelines, when smoking is advised (which it is generally not), initial dosing recommendations for smoked marijuana are usually for small amounts of lower-potency marijuana. For example, the starting recommended dosing is 1 inhalation of a “joint” (with up to a 9% THC maximum) once per day. This can be increased to a maximum recommended dose of 1 inhalation 4 times a day, resulting in approximately half a “joint” per day (or up to 400 mg). People should not operate dangerous equipment or perform potentially dangerous activities after use. This includes no driving for a minimum of 3 to 4 hours after inhaled medical marijuana, 6 hours after oral ingestion, and for at least 8 hours if they experience a subjective “high.”
Higher doses are sometimes used. It should be noted that if patients use a 5 gram (current maximum) dose of 15% THC, this represents approximately a 20 times higher dose than the recommended 400 mg of 9% THC. Higher doses, especially at this level are associated with significantly higher risk of adverse side effects (see below). In marijuana resin, which is commonly referred to as hash or hashish, the mean contents of THC, CBD, and CBN are 14.1, 2.5, and 1.9%, respectively. Other commercial products including oils and edibles may contain higher potencies still.
National Academy of Sciences
This website appears to be good resource for exploring medical marijuana.
- Simplified guideline for prescribing medical cannabinoids in primary care – Canadian Family Physician – 2018
- Physician Recommendation of Medical Cannabis Guidelines Calif Medical Assoc – 2011
- Prescribing smoked cannabis for chronic noncancer pain. Preliminary recommendations – Canadian Family Physician – 2014
Medical Marijuana – Vaping
- Drug Vaping – From the Dangers of Misuse to New Therapeutic Devices – 2016
- Drug vaping applied to cannabis – Is “Cannavaping” a therapeutic alternative to marijuana? – 2016
- Toking, Vaping, and Eating for Health or Fun: Marijuana Use Patterns in Adults, U.S., 2014. – PubMed – NCBI
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