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CBD Microcapsules Can Improve Absorption, Study Finds

By Alexander Beadle

Published: Jun 28, 2021   
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Novel microencapsulation technology can improve the bioavailability of cannabidiol (CBD) and its uptake in the brain, according to new research from scientists at Western Australia’s Curtin University.

In a new study, published in PLOS One and funded by industry partner Zelira Therapeutics, the researchers report that microcapsules of CBD can more effectively resist degradation from oxidation and stomach acid during ingestion and are able to enhance the absorption of CBD through the gastrointestinal tract and into the bloodstream.

In light of their findings, the researchers believe that such microencapsulation technology could provide a breakthrough in enhancing the bioavailability of CBD and its usefulness as a medical treatment for neurological diseases.

Improving the bioavailability of CBD

CBD has been shown to hold great therapeutic potential in the treatment of a wide range of medical conditions, including multiple sclerosis and Parkinson’s disease. But unfortunately for those who would like to see CBD-based medicines for these conditions become more common, the cannabinoid is an extremely challenging compound to work with.

CBD is naturally very lipophilic (meaning that it dissolves well in fats, but not in water), is sensitive to light exposure, and is largely broken down in the small intestine when it is ingested. As a result, the oral bioavailability of CBD oil is extremely low, roughly 6 percent.

By altering the drug delivery method for CBD, scientists hope to overcome these challenges and improve bioavailability so that the actual active dose consumed is higher. Scientists are also investigating the combination of CBD with other known absorption-enhancing agents to see whether this increases the amount of CBD that can cross over into the bloodstream.

“Cannabidiol is found in medicinal cannabis and is a popular natural remedy for people living with neurological and metabolic diseases. Due to limitations in absorption, we aimed to design and test a new drug delivery method,” said lead researcher and associate professor Ryu Takechi, in a statement.

“Our team was able to significantly improve the absorption and brain delivery of cannabidiol by administering it [CBD] in a novel microcapsule form, in combination with a naturally occurring bile acid.”

CBD microcapsules with an absorption enhancer improve short-term bioavailability

The CBD microcapsules used in this study were created using sodium alginate – a gelling agent extracted from seaweed – and calcium chloride. The process results in tiny capsules of CBD measuring just 0.4 millimeters in size. This microencapsulation technique was repeated on an absorption-enhancing bile acid, deoxycholic acid (DCA), to create similar DCA microcapsules.

Groups of three or four laboratory mice were administered either a standard CBD oil, CBD microcapsules, or a combination of CBD and DCA microcapsules. Plasma and brain samples were collected from the mice 20 minutes, one hour, and three hours after the drug had been administered to examine the short-term bioavailability of CBD.

The scientists found that after 20 minutes, CBD levels in the blood plasma of the group given CBD microcapsules were two times higher than those given regular CBD oil, indicating the improved uptake and short-term bioavailability of CBD in this form.

In the group given both CBD and DCA, concentrations of CBD in the brain after 20 minutes were seen to peak at a value 40-times higher than when using standard CBD oil. After one hour this concentration mellowed to match the concentrations seen in the other administration methods, but the cumulative CBD concentration experienced by the CBD and DCA group was still higher overall.

Microcapsule CBD as a treatment for neurological disease

Notably, the study does state that “the trends described did not reach statistical significance” using the one-way analysis of variance (ANOVA) statistical test. However, the authors believe that this is because of the small sample size used in this study, as they have previously conducted larger encapsulation studies on a drug with similar properties to CBD where absorption was significantly increased.

Despite this question of significance, the authors believe that this combination of CBD and DCA still does represent a promising avenue for future research.

“In this study, we were able to show for the first time that a bile acid actually increased the uptake and retention of cannabidiol within the brain. This shows that bile acids, could be used to enhance the delivery of cannabidiol when taken orally, particularly when treating neurological disorders,” Takechi said. “Further research is needed to test whether this type of drug delivery method could be successful in human studies, but our findings are very promising.”

Dr Oludare Odumosu, CEO of Zelira Therapeutics, added: “The new encapsulation technology appears to significantly improve the efficiency with which cannabinoid-based drugs can be delivered into the brain. This could lead to improvements in the effectiveness of cannabinoid therapies to treat neurological disorders while reducing cost and enhancing safety.”


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