While smoking some Sunlight in the sunlight of my bedroom, a problem popped into my head. The amount of chronic marijuana users will most likely escalate in the United States with more states legalizing recreational use in the following years. And while the science behind cannabis is complicated, it’s important for consumers to understand this science to help break the stigma behind cannabis use.

I’ve mentioned some basics about the metabolism of cannabinoids in a previous post here if you’d like to read a little more.

While I always try to simplify topics as much as possible, pharmacokinetics tend to be a tricky no matter what. To start, lets think of what our bodies do to the marijuana we injest. When someone takes a medicine, it goes through 5 major processes before reaching its final destination, known as the receptors. 

Below, I will explain each step of medication meatabolization with first a brief definition, then how this relates to cannabinoids. Thank you https://www.rxkinetics.com/pktutorial/1_2.html for the basic definitions.

The 5 Major Steps

Liberation – The release of the drug from its dosage form. If using a 10mg chewable THC tablet the chewing itself is manual liberation, but also the enzymes in your stomach and saliva help with chemical liberation. Just think of this as the medication freeing or liberating itself.

Absorption – The movement of drug from the site of administration to the blood circulation. Cannabinoids are highly lipophilic meaning they like fatty environments and the blood is mostly water which is one of the many reasons THC and CBD are both said to have poor oral bioavailability. Another reason why smoking marijuana gives most people a higher amount of the THC% per dose than eating it.

Distribution – The process by which drug diffuses or is transferred from intravascular space to extravascular space (body tissues). THC and CBD spread quickly in organs with high blood flow such as the brain, liver and heart with subsequent spread to other tissues.

With chronic use, cannabinoids can accumulate in fatty tissue. Therefore, a person’s body composition can drastically impact their dosage. The slow release of these cannabinoids from fatty tissue may result in cannabinoid activity lasting for several weeks after taking a dose.

Metabolism – The chemical conversion or transformation of drugs into compounds which are easier to eliminate. THC and CBD are both metabolized by the liver. Many of these enzymes are the reason only a small portion of orally ingested cannabinoids reach their target. They get broken down before having a chance to interact with their respective receptors. This is known as first-pass metabolism. Inhaling cannabinoids bypasses this metabolic step. Another reason it has a higher bioavailability relative to ingesting.

Elimination – The elimination of unchanged drug or metabolite from the body. Most cannabinoids are eliminated via the feces with a smaller percentage through urine. The time it takes to eliminate cannabinoids from your system varies based on patient factors such as body weight and dosage of the medicine.

This is just a surface-level look at the complicated pharmacokinetics of cannabinoids, but the more regular cannabis users embrace the legitimacy of the science behind what makes marijuana so useful, the more people will destigamtize it’s use.

References:

-Sharma P, Murthy P, Bharath MM. Chemistry, metabolism, and toxicology of cannabis: clinical implications. Iran J Psychiatry. 2012 Fall;7(4):149-56. PMID: 23408483; PMCID: PMC3570572.

-Toennes SW, Ramaekers JG, Theunissen EL, Moeller MR, Kauert GF. Comparison of cannabinoid pharmacokinetic properties in occasional and heavy users smoking a marijuana or placebo joint. J Anal Toxicol 2008; 32: 470–477.

-Grotenhermen F. Pharmacokinetics and pharmacodynamics of cannabinoids. Clin Pharmacokinet 2003; 42: 327–360.

-Lucas CJ, Galettis P, Schneider J. The pharmacokinetics and the pharmacodynamics of cannabinoids. Br J Clin Pharmacol. 2018 Nov;84(11):2477-2482. doi: 10.1111/bcp.13710. Epub 2018 Aug 7. PMID: 30001569; PMCID: PMC6177698