Bioavailability: What Is It And Why It Matters

Cannabinoids are a true treasure given to us by the plant kingdom, although perfectly suited to work in our endocannabinoid system; the difficulty comes in getting a cannabinoid delivered to your blood. The ways to deliver the cannabinoids are varied and diverse with them all having differing degrees of bioavailability. This bioavailability will be used to describe how much cannabinoid is delivered to your blood by various methods of intake and represented typically as a percentage. As there are many variables involved the below guidelines will be general but relatively accurate.

Cannabinoid pharmacokinetics: The various biological systems that process the cannabinoid

Cannabinoid pharmacokinetics encompasses absorption after diverse possible routes of administration and from different drug formulations, until its elimination in the feces, urine, sweat, oral fluid, and hair. These points of elimination are also generally how people get tested for use. So to put in general terms we will look at if you intake “x” quantity of cannabinoids what percentage of that quantity can possibly make it to receptors. By understanding this process, we can also do certain things to enhance the bioavailability, such as the intake of lipids with edible cannabinoids.

Cannabinoid Solubility: Cannabinoids will not dissolve in water

Chemically speaking cannabinoids have poor solubility in water, but good solubility in most organic solvents, such as alcohol and lipids. This is why cannabinoids will not readily dissolve in water unless “nano” or “water soluble” products which will be discussed later. The solubility issue really comes into play when talking about edibles. As we know our bodies are water based in its cellular processes. Since cannabinoids are not water soluble, they tend not to be easily absorbed in our digestive system. Fortunately cannabinoids are soluble in lipids and our bodies make enzymes which help digest them and the cannabinoids are pulled with them, greatly increasing the bioavailability.

First-Pass effect: All orally administered cannabinoids must past this barrier

The first pass effect is a process of drug metabolism whereby the drug concentration, when administered orally (edible or sublingual), is greatly reduced before it reaches the systemic circulation. The first pass effect is the fraction of drug lost during the process of absorption and is very different then bioavailability. The first pass effect is generally related to the liver and gut wall and there are many compounds subject to this process, cannabinoids being one of them. This is where solubility comes into play, as mentioned the cannabinoid dissolved with lipids such as a greasy hamburger will greatly increase the amount of that makes it past this barrier.

Blood Brain Barrier (BBB): The last barrier to overcome

The greater limiting factor in the bioavailability of cannabinoids is the blood–brain barrier (BBB). The BBB is sort of a network of brain microvessels that is very selective in what it allows to pass through it. Fortunately cannabinoids pass through the BBB and crosses over into the fluid within the central nervous system. The target receptors lay on the other side of the BBB and must pass through it to gain access to the receptors. The BBB is a complex system that protects our neurons and is the last hurdle in cannabinoids gaining access to receptors.

Cannabinoid Edibles: The most safe and delicious way to consume cannabinoids but the least bioavailable

Classic edibles the type we all chew and swallow with favorites from gummy bears to the tried and true brownie. Brownies or any type of edible high in lipid content will be a better edible as far as the bioavailability is concerned. After oral administration, THC is absorbed more slowly and unpredictably with a peak in concentration generally obtained after one to three hours. The cause of this is restriction mainly with the first pass effect. Many studies have been done on the bioavailability of cannabinoids as edibles with the results being surprising. The percentage varies between individual cannabinoids but the actual numbers are typically in the 2% to 20% actual percentage that makes it to your blood and with likely only 1% of that making it past the BBB, what it shows is how powerful cannabinoids really are. By far the most commonly available edible is gummies, they are easy to make and easy to consume in public without strange looks. They typically lack lipids though and taking gummies alone will result in the low end of the percentage noted. There is the simplest correction to increase the bioavailability, that is to eat with some form of fat or oil, which will surprise you with the difference.

“Nano-Emulsification” and “Water Soluble”: effective way to increase bioavailability substantially.

Nano-cannabinoids, one of the newer methods of cannabinoid administration which also greatly increases their bioavailability. What in general terms is happening is that as mentioned before cannabinoids are not water soluble, but by attaching each cannabinoid molecule to a different molecule that changes the cannabinoid to become soluble in water. This means that now you can buy water soluble THC and add it to your favorite energy drink to give it more of a kick. There are many different processes to make cannabinoids water soluble and most methods are not readily given out. It is known that it greatly increases the ability to allow cannabinoids to make it past the first pass effect.

Oral Cannabinoids: Tinctures and hard candies that qualify as sub-lingual.

Sub-lingual bioavailability is greatly increased when compared with the classic edibles. The mucous membranes locate in the mouth have a much higher absorption rate for cannabinoids when compared to the gut, with percentage of bioavailability beginning at the upper range of edibles. A good comparative method to illustrate this is the absorption of nicotine via the mouth with snuff or chewing tobacco. It is an effective method for drug delivery and is superior to gut absorption. The process once absorbed follows the same routes but just is much more effective. A tincture must be held in your mouth as long as you can. The longer you can hold it without swallowing the more effective it will be. A really good method is to make hard candies like life savers or even mints but something tasty that you can let slowly melt in your mouth without swallowing, this actually makes a big difference in my own personal experience.

Vaped or Smoked: The most effective means outside intravenous (never recommended)

The most bioavailable methods of administration are by heating cannabinoids to their respective boiling point and inhaling the vapor. The difference between smoking and vaporization is temperature dependent. The higher the temperature the vapor gets, the more potential damage it can cause due to many unknown compounds being formed at high temperatures. Compared to combustion, vaping can be considered a safer and potent way to administer cannabinoids. The temperature of vaping is typically right above the boiling point of cannabinoids while the temperature of combustion can be double that. Researched bioavailability rates have shown up to 60% with this form of administration. It should be also noted that with inhalation of vapor, the onset of effects is much more rapid, often within seconds. Other variables affecting bioavailability within this method is the number, duration, and spacing of puffs, hold time, and inhalation volume, or smoking topography. While this could be considered not as safe as oral administration, it clearly is the most common and powerful method readily available.


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