Cannabidiol, commonly known as CBD, is a compound found in the cannabis plant. It is distinct from tetrahydrocannabinol (THC) because it does not produce intoxicating effects. Understanding how the body processes CBD is important for comprehending its potential effects and safety. This journey involves several steps, from its initial entry into the body to its eventual elimination.
How CBD Enters the Body
When CBD enters the body, it must be absorbed to reach the bloodstream. The method of administration influences this absorption, determining its bioavailability—the proportion of CBD that enters circulation and can have an active effect.
Oral ingestion, like CBD oils or edibles, results in lower bioavailability due to the “first-pass effect.” Here, CBD is metabolized by gut and liver enzymes before fully entering systemic circulation, breaking down a significant portion.
Sublingual administration, where CBD oil is held under the tongue, allows for direct absorption into the bloodstream through mucous membranes, bypassing the digestive system and the first-pass effect. Inhalation, through vaping, offers rapid entry into the bloodstream via the lungs, providing quicker effects. Topical application, like creams or balms, primarily interacts with cannabinoid receptors in the skin and typically does not lead to significant systemic absorption.
The Liver’s Role in CBD Breakdown
Once in the bloodstream, the liver primarily breaks down CBD. This organ contains the cytochrome P450 (CYP450) enzyme family, which processes foreign compounds like CBD by transforming them into different molecules.
Specific CYP450 enzymes, particularly CYP2C19 and CYP3A4, are involved in initial CBD metabolism. They perform hydroxylation reactions, adding hydroxyl groups to the CBD molecule, converting it into various metabolites.
A primary metabolite formed through this process is 7-hydroxycannabidiol (7-OH-CBD). This metabolite is then further oxidized by other CYP450 enzymes into 7-carboxy-cannabidiol (7-COOH-CBD). While 7-OH-CBD may retain some biological activity, it is generally considered less potent than CBD itself, and 7-COOH-CBD is largely inactive.
These metabolic transformations modify CBD into forms easier for the body to excrete. This breakdown pathway ensures CBD does not accumulate indefinitely.
How CBD Leaves the Body
After liver metabolism, CBD metabolites undergo further processing for removal. Glucuronidation is a significant step, involving conjugation of metabolites, especially 7-OH-CBD and 7-COOH-CBD, with glucuronic acid.
This conjugation reaction makes the metabolites more water-soluble. Increased water solubility allows these compounds to dissolve more readily in bodily fluids, making them easier to excrete. Without this modification, the fat-soluble CBD and its initial metabolites would be more difficult to eliminate.
The majority of these water-soluble CBD metabolites are then excreted from the body through two primary routes: urine and feces. The kidneys filter the blood, removing water-soluble waste products, which are then expelled in urine. Some metabolites are also secreted into bile by the liver, which then travels to the intestines and is ultimately eliminated in feces.
What Affects CBD Processing
Several factors influence how an individual processes CBD, affecting its effects and duration. Genetic differences in CYP450 enzymes, particularly CYP2C19 and CYP3A4, can alter how quickly and efficiently CBD is metabolized.
An individual’s liver function also plays a role, as a healthy liver is necessary for efficient CBD metabolism. Age can influence processing, with metabolism potentially slowing in older individuals. Diet and overall health status can also subtly impact enzyme activity and metabolic rates.
An important consideration is drug-drug interactions. CBD can inhibit certain CYP450 enzymes, like CYP2C19 and CYP3A4, which metabolize many common medications. This inhibition can lead to higher concentrations of other drugs, potentially increasing their effects or side effects. Consulting a healthcare professional is advisable when considering CBD use alongside other medications.