One of the critical factors that influences Cannabidiol (CBD) efficacy is bioavailability. Bioavailability in this case refers to the proportion of CBD that enters the bloodstream when introduced into the body and is available for use or storage. The bioavailability of CBD varies significantly depending on the form in which it is consumed. In this part we will explore the bioavailability of CBD across different administration routes, including oral, sublingual, inhalation, and topical methods, and discuss the factors influencing these variations.
CBD Edibles and Capsules (oral administration)
Oral administration, including edibles, capsules, and beverages, is one of the most common ways people consume CBD. However, this method is also associated with the lowest bioavailability, typically ranging between 6% and 19%.
When CBD is ingested orally, it passes through the digestive system where it undergoes first-pass metabolism in the liver. This process significantly reduces the concentration of CBD that eventually reaches systemic circulation.
There are certain factors that can influence the bioavailability of ingested CBD, such as food intake. The presence of food in the stomach, particularly fatty foods, can enhance the absorption of CBD. This is because CBD is lipophilic, meaning it dissolves more readily in fat, which can increase its absorption.
CBD Oils and Tinctures (sublingual administration)
Sublingual administration involves placing CBD oil or tincture under the tongue, allowing the compound to be absorbed directly into the bloodstream through the mucous membranes.
By bypassing the digestive system, sublingual administration results in a higher bioavailability compared to oral ingestion. The bioavailability of sublingual CBD is estimated to be around 13% to 35%, though this can vary based on individual factors.
Sublingual administration offers the advantage of a faster onset, with effects typically beginning within 15 to 30 minutes, as the CBD enters the bloodstream directly. Additionally, this method provides higher bioavailability by bypassing the digestive system, reducing the breakdown of CBD and allowing more of the compound to reach systemic circulation. Also, the amount of time CBD is held under the tongue can impact the amount absorbed. Longer hold times can lead to higher bioavailability (at least 1 min).
Inhalation of CBD - Smoking and Vaping
Inhalation methods, including smoking CBD-rich cannabis or vaping CBD oil, offer one of the highest bioavailability rates, ranging from 31% to 56%.
When CBD is inhaled, it is absorbed through the alveoli in the lungs, which provides a large surface area for rapid absorption into the bloodstream. This method bypasses the digestive system and liver metabolism, resulting in a higher concentration of CBD entering in circulation.
In addition to the high bioavailability of CBD through inhalation there is another advantage. The effects of inhaled CBD are almost immediate, typically felt within minutes. This is an attractive option for those seeking quick relief.
Topical CBD Application
Topical CBD products, such as creams, balms, and lotions, are applied directly to the skin and are primarily used for localized relief.
When applied topically, CBD interacts with cannabinoid receptors in the skin but does not typically enter the bloodstream in significant amounts. This means that the bioavailability of topical CBD is negligible, as it does not reach systemic circulation. Topical CBD is effective for targeting specific areas of the body, such as muscles or joints, where it may help reduce inflammation and pain.
Usually, topical CBD products contain ingredients such as liposomes or permeation enhancers, that improve skin penetration and efficacy of the CBD.
Intranasal Administration
Although less common, intranasal administration of CBD involves spraying or inhaling CBD into the nasal passages. This method offers bioavailability between 34% and 46%, with effects felt within minutes. The nasal mucosa provides a direct route to the bloodstream, bypassing the digestive system and first-pass metabolism. This leads to rapid absorption and relatively high bioavailability.
