What is CBD Bioavailabilty: Why Does it matter?

Cannabidiol or CBD – a popular option for those looking for alternative methods of treating different “untreatable” symptoms and ailments – is available in the market in many forms: tinctures, oils, lotions and creams, e-liquids, capsules, vapes, gummies, etc.

But which form is the most effective to you and how much to use to get the most effect from it?

Each of these forms has different ways of administering and their effects take varying time period to kick off and remain in your system. Which raises another question: Which method of administering is most suited for you?

While options can be a boon for some users, it can also be very confusing for others. This is where the concept of bioavailability comes into the picture.

CBD Bioavailability

According to the Merck Manual of Diagnosis and Therapy Manual [8], Bioavailability is the “extent and rate at which a drug enters the systemic circulation, thereby accessing the site of its (intended) action”. It is “largely determined by the properties of the dosage form, which depend partly on its design and manufacture”.

The manual explains how the same drug can have different bioavailability depending on the way they are composed, the presence of other elements and the form in which they are made and administered. It also elaborates on how these differences can have a different clinical impact on the user.

This explains why understanding the bioavailability of a drug is essential for a user. Cannabidiol, like any other drug, has different bioavailability depending on the form in which we use it. But, to understand CBD’s bioavailability, we must first get a clear idea of how CBD enters our system and takes effect.

CBD pathways

To have an effect on your body, CBD must travel from the administration site to the bloodstream, from where it is automatically transported through the cannabinoid receptors (CB1 & CB2) of the endocannabinoid system [1] and other non-cannabinoid receptors like serotonin receptor (5-HT1A).

This is a two-step pathway:

  • The path that a CBD product takes to be administered is the route of administration. The way you use, i.e. apply or consume, decides the speed at which a CBD product takes effect, the quantity required to stay active in the body, and how long the effects will remain.
  • Next, comes the process of absorption. CBD is transferred from the site of application into the bloodstream. This is where bioavailability or simply its effectiveness comes into play. Measured as a percentage, the bioavailability number stands for the total amount of the substance absorbed and put to active use.

Now that we understand how CBD works in our body, let us check out how each form of cannabidiol product acts on our body.

Bioavailability of Different Forms of CBD

As mentioned earlier, CBD can be used in different forms. Different forms of this phytocannabinoid have different bioavailability. Let us check each type out one-at-a-time:

  • Intravenous Injection: To get the maximum bioavailability out of your CBD, the most direct route is through an intravenous injection. While this may mean getting 100% bioavailability, this isn’t the most popular method of administration. Most people who are tired of the usual methods of treatment don’t like to stick themselves with a needle.
  • Oral Administration (Capsules and edibles): The easiest and the most popular way of using CBD is by consuming it, in the form of capsules, tablets or other edibles, like gummies. In this process, the cannabinoid enters our digestive system before it is absorbed into the bloodstream. For this, CBD must pass through the portal vein to enter the liver where it is metabolized.

The problem with this kind of CBD administration is that the enzymes in the liver reduce CBD’s concentration before it can reach the bloodstream, hence, reducing its effectiveness.

According to a 1986 study [3], published in the Biomedical & Environmental Mass Spectrometry, ingested CBD has only a 6% bioavailability. However, another study [4] conducted in 2009 reported it to be somewhere between 4% – 20%. Both, admittedly, aren’t that high, meaning to say you lose over 75% of the CBD actually ingested.

  • Sublingual Concentrates (Tinctures and Sprays): When an isolate, a tincture, lozenge or spray is administered under the tongue, the sublingual gland, located there, absorbs CBD directly into the bloodstream.

The process of using CBD this way is to hold the liquid or lozenge for around 60-90 seconds before swallowing it down, which is absorbed into the bloodstream through the digestive system.

This is a better mode of administering than oral consumption as it does not depend entirely on the digestive system.

Passage of CBD through the mucous system is much faster and more effective than through the digestive system.

According to a 2012 study [5], this method of administering has 12%-35% bioavailability, significantly higher than oral consumption.

The issue with this method of administering is cannabis taste. However, many companies these days use flavor additives to mask it.  

A major problem with both the above forms of CBD products is that CBD, like most other cannabinoids, is not water-soluble, only fat-soluble. When they are consumed with fat, it can be processed more effectively by the body.

So, products that aim at administering CBD orally as pills or edibles or as tinctures or sprays to be used sublingually are prepared with an oil carrier to be effectively absorbed.

However, with significant technological improvements in the CBD processing methods, scientists have come up with new kinds of products that address bioavailability issues.

These new technologies break up the CBD oil particles into tiny pieces, suspending them in a liquid form that is easily absorbed into the bloodstream without requiring fat carrier or fatty food. Such processes increase the effectiveness of CBD by 200-500% compared to traditional oil-based products.

  • Inhalation (Vaporized, Smoked & Dabbed): CBD inhalation is one of the most popular, and perhaps the most effective way to administer the substance. Inhaling CBD through a vape pen or vaporizer device is believed to have five times higher bioavailability than oral ingestion, owing to the highly permeable surface of the lungs inner walls.

According to a 2010 study [6], this method of administration has between 34–46% bioavailability, while another study, conducted in 2007 [7] shows that by vaporizing this cannabinoid product, CBD bioavailability can rise up to even 56%.

While this may be the most effective way of administering CBD, it poses the same risks linked with regular vaping.

  • Topical (Lotions, Balms, Salves & Patches): Applying CBD directly on the skin is another popular method of administration. A wide variety of creams, lotions, balms, massage oils, and salves are available in the market these days.

These products are designed to target cannabinoid receptors found in the skin to get rid of aches, sores, and other skin issues.

Anecdotal feedback has displayed evidence of an increase in the popularity of topical CBD products among a lot of people, including sportspersons.

  • Suppository: This is the least popular of all the above methods of administration. For obvious reasons, of course! No one likes to push a medicine up to his or her anus. Even so, suppositories have been seen to be highly bioavailable and thus a highly effective use of CBD. However, it is quite useful for people who are in desperate need of it to treat or manage their symptoms.

This method of CBD administration usually shows noticeable effects within 15 minutes, and its effects can last for almost 8 hours– which is longer than all other forms of CBD administration.

Foods to boost the bioavailability of oral CBD consumption

If you prefer to ingest CBD, you may want to consider eating foods that enhance its bioavailability. According to most scientists, fatty acids and medium- to long-chain triglycerides boost the bioavailability of oral CBD.

Fat acts as a binding agent that allows CBD to attach itself to it. As the fats are metabolized into energy, so are the CBD absorbed into the bloodstream. This way, CBD can bypass reduction by the first metabolism and increase its effectiveness by four times.

Foods that are compatible with CBD include:

  • Coconut oil
  • Olive oil
  • Soybean oil
  • Sesame oil
  • Fish
  • Nuts
  • Avocado
  • Meat
  • Eggs

CBD Bioavailability of Isolate vs Full Spectrum

  • CBD Isolate: Chemists have recently found ways to “isolate” cannabidiol from the 84 other active cannabinoids in cannabis. Isolated CBD is a more stable compound and has virtually no THC, which has the potential of many harmful effects on the body, not mentioning the trouble it can get people in, legally.
  • Full-Spectrum CBD: CBD full-spectrum, which is produced through a more gentle process, does have certain levels of THC, among other cannabinoids, in it. Their presence brings us to the “Entourage Effect” – which is what apparently improves the bioavailability and efficacy of the CBD. Although, a lot more research and tests need to be done to prove the entourage effect, it did seem to help treat certain conditions and diseases, like cancer, for instance [2].

It is often believed that using or consuming substances in the form that nature intended them to be are, in fact, the best way to take them. For example, coca leaves aren’t dangerous until they are distilled and synthesized to create cocaine. In fact, many advocates of CBD claim that the full-spectrum form is the most effective, no matter what the ailment.

Our Takeaway

Even though it may sound a little complicated, CBD bioavailability, like any other drug bioavailability, is important to understand which method of administration is most effective and comfortable for use for any individual user, as well as its effectiveness in general.

For all those first-time users and also those looking for better ways of using CBD, we earnestly hope that this article will be of some help in clearing all your doubts.

However, we do urge every user to consult a doctor before considering CBD as an alternative treatment for their ailments.

  1. An introduction to the endogenous cannabinoid system; Biological Psychiatry; October 30, 2015; Hui-Chen Lu1, and Ken Mackie; https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4789136/
  2. Appraising the “entourage effect”: Antitumor action of a pure cannabinoid versus a botanical drug preparation in preclinical models of breast cancer; Biochemical Pharmacology; June 27, 2018; Blasco-Benito S, Seijo-Vila M, Caro-Villalobos M, Tundidor I, Andradas C, García-Taboada E, Wade J, Smith S, Guzmán M, Pérez-Gómez E, Gordon M, Sánchez; https://www.ncbi.nlm.nih.gov/pubmed/29940172  
  3. Single-dose kinetics of deuterium-labelled cannabidiol in man after smoking and intravenous administration; Biomedical & Environmental Mass Spectrometry; February 13, 1986; Ohlsson A, Lindgren JE, Andersson S, Agurell S, Gillespie H, Hollister LE; https://www.ncbi.nlm.nih.gov/pubmed/2937482
  4. Human Cannabinoid Pharmacokinetics; Chemistry & Biodiversity; August 4, 2007; Marilyn A. Huestis; https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2689518/
  5. Subjective and physiological effects of oromucosal sprays containing cannabinoids (nabiximols): potentials and limitations for psychosis research; Current Pharmaceutical Design; 2012; Schoedel KA, Harrison SJ; https://www.ncbi.nlm.nih.gov/pubmed/22716155
  6. Cannabidiol bioavailability after nasal and transdermal application: effect of permeation enhancers; Drug Development and Industrial Pharmacy; September 3, 2010; Paudel KS1, Hammell DC, Agu RU, Valiveti S, Stinchcomb AL; https://www.ncbi.nlm.nih.gov/pubmed/20545522
  7. Human Cannabinoid Pharmacokinetics; Chemistry & Biodiversity; August 4, 2007; Marilyn A. Huestis; https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2689518/  
  8. Drug Bioavailability; Merck Manual of Diagnosis and Therapy Manualhttps://www.merckmanuals.com/professional/clinical-pharmacology/pharmacokinetics/drug-bioavailability