Bioavailability and CBD
Here’s what bioavailability is and what CBD oil values are
Before starting any treatment either based on CBD or another compound we must understand how our body will react to the dose we consume. A thorough study of the amount our body will assimilate is essential to obtain the results we want. There are several factors that make each person need a different amount of the same substance and the bioavailability of a drug plays a very important role.
In the first moment we will define some pharmacological terms that will help us throughout the text to understand much better the complex concepts that will help us choose the ideal dosage.
Its etymology already gives us a clue as to what this branch of science can treat. On the one hand “Pharmaco” tells us that it is related to Pharmacology and “Kinetics” we can infer that it has to do with something that is in motion. Indeed, Pharmacokinetics studies how drugs move through our body, from entering to leaving our body.
It refers to where a substance enters our organism. It can be intravenous, oral, topical, rectal, etc…
It is the target organism on which drugs work. They are usually proteins, lipids and nucleic acids.
In Pharmacokinetics, absorption of the drug penetration process by cell membranes to reach the blood is called absorption. Intravenous administration skips the absorption process directly.
It refers to how the drug travels through the blood to the different tissues of the body.
Our body transforms drugs into by-products to facilitate their elimination. A drug that is supplied orally will always go through the metabolic filter which will break it into by-products and not pass into the bloodstream at 100%
It’s the process by which our body ends up removing the drugs
It is the amount of drug that passes into the bloodstream and is available to our body.
So what is Bioavailability?
In Pharmacokinetics the Bioavailability of a drug is part of the study of absorption and is the percentage and rate at which the compound reaches plasma in our systemic circulation. Therefore, if a medicinal product is delivered intravenously (IV), by definition, its Bioavailability is 100%. Our body would then have 100% of the compound available in the circulatory system to achieve the therapeutic target.
Therefore, we can infer that to calculate the bioavailability of a drug it is essential to differentiate the routes of administration. The following table details the bioavailability for each pathway:
The most common and safest way to take any drug at home is oral. When we ingest a medicine it is absorbed by the liver that is responsible for passing it into the bloodstream. However, not all of the drug reaches our systemic circulation, as the liver first step metabolism breaks down some of the active substances that will never circulate through our body. Therefore, when we want to calculate the bioavailability of a drug administered orally we should also take into account this effect of metabolism of first hepatic step.
Some compounds (such as CBD that we will discuss later) have a great first-step effect so administered orally do not achieve enough plasma concentration to achieve the therapeutic target. In these cases it is indicated to look for an alternative route of administration. The most common and safest way to take any drug at home is oral. When we ingest a medicine it is absorbed by the liver that is responsible for passing it into the bloodstream. However, not all of the drug reaches our systemic circulation, as the liver first step metabolism breaks down some of the active substances that will never circulate through our body.
Therefore, when we want to calculate the bioavailability of a drug administered orally we should also take into account this effect of metabolism of first hepatic step. Some compounds (such as CBD that we will discuss later) have a great first-step effect so administered orally do not achieve enough plasma concentration to achieve the therapeutic target. In these cases it is indicated to look for an alternative route of administration.
Sublingual administration,for example, increases the bioavailability of the drug since under the tongue we have countless capillaries and the tissue is permeable enough for the substance to pass directly into the bloodstream. A couple of examples of bioavailability of some drugs we’re more familiar with:
- Ibuprofen orally: 49-73%
- Paracetamol orally: 63-89%
- Oral Aspirin: 80-100%
- Amoxicillin orally: 95%
Other factors that influence the bioavailability of a drug include:
- Patient’s age
- Patient weight
- Other substances consumed by the patient simultaneously
- Patient’s illnesses or dysfunctions
The bioavailability of nutrients in food
The study of the bioavailability of nutrients in food is fundamental to understanding how to feed the entire population with the available resources. This is why enormous efforts are being made to understand the bioavailability of the nutrients in each food and which factors of the individual can influence it.
Macronutrients (proteins, carbohydrates and fats) achieve a bioavailability of up to 90%. Since macronutrients enjoy such high bioavailability, the biological value is given great importance, for example, we prefer unsaturated fats rich in omega 3, 6 and 9 acids and proteins that contain the greatest amount of essential amino acids that our body is not able to synthesize.
However, the study of the bioavailability of micronutrients such as vitamins and minerals is much more complicated as their digestive process is more complex and involves much more factors that alter the bioavailability of these in each individual.
What is the bioavailability of CBD oil? What is the optimal route of administration?
Many times we look at the concentration of oils before we stop to think about exactly how much we need to treat our problem. This is why, next, we will try to understand how our body absorbs CBD. Remember that the route by which we administer it will determine its absorption and bioavailability.
One of the most common routes of administration is in edible capsules that will pass through our digestive system and CBD will be absorbed by the liver. CBD has a fairly high liver first-step metabolism effect, so our liver will decompose it leaving a bioavailability of as low as 4% – 20% (according to recent studies). Of course the industry is trying to respond to this CBD bioavailability problem orally and by investigating water-soluble emulsions that increase absorption and bioavailability by up to nearly 50%. If we opt for this route of administration we should also take into account whether our stomach is empty or full before consuming the capsules. CBD is fat-soluble which if we accompany it with high-fat meals we can increase its bioavailability orally.
CBD concentrates sublingually
Sublingual administration of any drug will automatically increase the bioavailability of the drug as the mucous membranes will absorb part of the active substance directly into the bloodstream. To do this, you’ll need to keep the oil droplets for 90 seconds under your tongue before swallowing them. With sublingual administration you can achieve 12% to 35% bioavailability of CBD.
E-liquid vaping (inhalation)
When vaping CBD oils we inhale the compound that reaches our lung. The pulmonary alveoli will be responsible for transporting the active substance very quickly into the bloodstream so that the absorption will be almost instantaneous and a bioavailability above 50% can be achieved.
There are countless creams and balms with CBD as an active substance. The skin is a very dense membrane and low permeability which directly affects absorption. It is for this reason that if we choose the topical route to enjoy the benefits of CBD we will have to look a lot at the concentration of Cannabidiol of such products. This is the best way to soothe localized pains, dense layers of product should be applied to the skin and let it work until the skin finishes absorbing. In any case, applying any concentration of CBD to the skin will not get it into the bloodstream, so its bioavailability is nil. There are transdermal CBD patches which are absorbed into the bloodstream, but their exact bioavailability is not yet known.
Synergies that increase bioavailability: Terpenes, Flavonoids and other Cannabinoids
So far we have talked only about the bioavailability of isolated CBD cannabinoid. Some studies show that combining CBD with other cannabinoids and terpenes naturally present in the hemp plant such as guaiol ocimene or humulene increases the bioavailability of the compound by any route of administration.
In the market we can find:
- Broad Spectrum CBD Oil: Contains CBD with some (not all) of the cannabinoids, terpenes and flavonoids of hemp.
- CBD Full Spectrum Oil: Contains all cannabinoids, terpenes and flavonoids of hemp. For all Higea CBD oils, the THC concentration is less than 0.2% which prevents psychoactive effects.
How long does it take for our body to completely eliminate CBD?
Depending on the dose and the route of administration our body will take more or less time to distribute and remove CBD from our system. The effects can several to 8 hours and their complete elimination does not usually exceed one week.
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