A major problem in the cannabidiol industry is the spread of misinformation, whether intentionally to mislead and sell products or accidentally because there is a lack of standardized information and training. There seems to be some confusion among a few CBD suppliers and other informational sources regarding the bioavailability of vaporized cannabidiol. For the simplest description, bioavailability means the percentage of a dose that is absorbed into the bloodstream, compared to the percentage of a dose after intravenous administration. The intravenous dose is considered to be 100% bioavailability, and all other routes of administration are compared to the intravenous route as a percentage. However, this article is not about the bioavailability of cannabidiol, but rather the spread of misinformation in regard to the inhaled bioavailability of vaporized CBD products.
I repeatedly come across articles claiming the bioavailability of inhaled CBD is 40 percent. However, I have never seen a research article with data supporting this claim. I believe someone did not actually read the article these sources are citing (if they cite any source at all) and others have followed blindly, claiming the same information without spending time to read the article they cite evidently.
The main source which I am most concerned about is Medscape, because it is considered a source of medical information. As they claim, it is the "Top Medical Resource for Physicians Today." Medscape has an article titled “Medical Marijuana: The State of the Science.” This article contains a section, called "The Dosing Dilemma with CBD," that claims:
“Bioavailability also varies greatly depending on route of administration of CBD. Studies have demonstrated bioavailability of the administered dose of 34%-46% for intranasal administration and 40% for vaporization. In contrast, the bioavailability of oral CBD is thought to be as low as 6%, owing to significant first-pass metabolism.”
When the source  is found in the references, this is the article cited:
- Solowij N, Broyd SJ, van Hell HH, Hazekamp A. A protocol for the delivery of cannabidiol (CBD) and combined CBD and ∆9-tetrahydrocannabinol (THC) by vaporisation. BMC Pharmacol Toxicol. 2014;15:58.
The full text for this article is available online, which makes the situation worse in my opinion. I would understand the error more if fewer writers were able to access the article to read it… however, the full text is available here.
The paper does not even have to be read, only the abstract needs to be glanced over, to clearly understand there are no human subjects involved in the study. There are no animals. There are not even cell lines or any model of a biological system utilized in the research. This article specifically measures the amount of CBD vaporized into a balloon. The data that indicates a 40% availability is based on the amount of CBD that was initially used in the vaporization device compared to the amount of CBD that was in the balloon after vaporization. It was never inhaled by any animal, and thus the levels of cannabidiol in the blood were never measured. Without this data, the article makes absolutely no claim about bioavailability.
These articles on the following sites also inaccurately make claims about the inhaled bioavailability of cannabidiol as of April 30, 2018:
https://news.medicalmarijuanainc.com/understanding-bioavailability-medical-cannabis/ (this article cites Medscape)
http://bhangers.com/resources/science/bioavailability-cbd-varies/ (article cites sources not containing any claim of 40% inhaled bioavailability)
https://www.leafscience.com/2018/01/25/vaping-maximizes-bioavailability-cbd/ (this article actually claims 50-60% peak CBD bioavailability without sources, likely referring to inhaled THC bioavailability at 56%)
The most cited inhaled CBD bioavailability research occurred over 30 years ago. Although it was for smoked CBD, rather than vaporized, it does provide a starting point for data regarding the inhaled bioavailability of cannabidiol. The reported bioavailability has a very wide range between subjects, with an average of 31% (+/- 13%).
My intention for this article is to highlight a bigger problem when obtaining information about CBD and cannabinoids in general. There needs to be more research to provide scientific data on the basic properties of cannabinoids and their biological properties. Once more data exists, less confusion will surround the use of cannabinoids. Until then, CBD suppliers need to be diligent to ensure they only provide information to consumers that is accurate and based in scientific data. If they do not understand the sources they are using, they should not make any claims that could potentially mislead those unfamiliar with the use of cannabinoids.
Most customers are using CBD without direction and supervision of a medical professional, so they depend on the guidance CBD suppliers provide and on the information they can find online. Here at Discover CBD, we undergo a minimum of 3 weeks of training to ensure our representatives understand the basics of CBD and the products we supply to our customers. People interested in using CBD most often turn to those of us in customer service for guidance, because there are very few resources for information. We all need to strive to provide the most accurate information possible to protect our customers and the cannabidiol industry as a whole.