Nailing the Science Behind CBD

Introduction

Cannabidiol (CBD) is a non-psychoactive cannabinoid compound, derived from the Cannabis sativa plant, that can be extracted either for medicinal use or as a nutritional supplement. Over the years, there is accumulating evidence that cannabinoids are beneficial for a range of conditions, such as pain, inflammation, epilepsy, sleep disorders, multiple sclerosis, anorexia, and schizophrenia, and CBD itself is generally well-tolerated with a good safety profile. In the 2018 Farm Bill, hemp—defined as cannabis and cannabis derivatives with no more than 0.3% THC (Tetrahydrocannabinol) by dry weight—was removed from the US Controlled Substance Act. In the same year, the US FDA approved the first CBD-based drug to treat two severe forms of epilepsy: Lennox-Gastaut syndrome and Dravet syndrome [1].

Figure 1a. Molecular structure of CBD.

Figure 1b. Molecular structure of THC.

As a result of these legal and regulatory changes, there is increasing public and clinical interest in using exogenous cannabinoids for a variety of commercial CBD applications, ranging from topical hand creams, to CBD-infused coffee, to dietary supplements. Many of these products are marketed to alleviate anxiety, reduce inflammation, and improve sleep quality. However, outside of the epilepsy indication, the lack of well-controlled clinical trials, low oral bioavailability, long half-life, and highly lipophilic nature of these compounds are major challenges for the pharmaceutical development of cannabinoids. There is also interest in the use of CBD and THC for diseases and symptom management, but limited information is available regarding their pharmacokinetic (PK) and pharmacodynamic (PD) properties.

Despite these challenges, further CBD research can potentially reveal a wide range of therapeutically promising pharmacological effects, either as an individual botanical drug substance or in combination with other drugs. But even with a lack of understanding in the mechanism of action [2], the cannabis market continues to grow following decriminalization and legalization efforts spearheaded by state legislation. This market includes both recreational cannabis products and novel pharmaceutical formulations designed to take advantage of the beneficial biological effects of cannabis.

However, for drug development applications, one of the challenges researchers face is differentiating between CBD and its stereoisomer, Δ-9-THC. Not only are CBD and Δ-9-THC two of the more notable cannabinoids found in cannabis with structurally similar profiles, they are both also attributed to therapeutic and psychoactive effects. The use and approval of botanical drug substances for medicinal benefits—including CBD—is complex due to the inconsistency in correlating single compound amounts to pharmacodynamic outcomes [3]. For recreational use, challenges arise with label accuracy issues in cannabis products [4], limiting the potential development of this class of compound as a viable drug-like molecule [5].

Methods

Quantifying CBD and Δ-9-THC becomes a very important factor in understanding cannabis product potency, efficacy, and safety. On top of that, the short half-life of the major CBD and THC metabolites may require additional toxicological analysis. These components are critical for determining beneficial attributes as well as psychoactive potential.

Fortunately, the laboratory here at Emery Pharma has the analytical capability of identifying and quantifying four major cannabinoid components. One of these major components is a metabolite formed in the human body, called 11-OH-Δ-9-THC, a compound that can be as equally potent as Δ-9-THC [6]. On top of that, many new products were recently identified to contain a compound called Δ-8-THC, which also happens to have a similar biological effect as Δ-9-THC [7]. We have developed analytical methods for cannabinoid isolation and identification and can achieve low ng/mL sensitivity for all of these compounds. This knowledge of chemical composition and metabolic pathways is a key factor for the development of botanical drug products. Additionally, Emery Pharma has the capability to assess biological activity and pharmacokinetic properties of these compounds.

Figure 2. Representative LC-MS/MS chromatogram detecting 11-OH-Δ-9-THC, CBD, Δ-9-THC, and Δ-8-THC.

During the development of these analytical methods, Emery Pharma scientists have identified potential stability issues in cannabis-derived products that other labs may have overlooked. Our experience has led us to investigate the critical property of cannabinoid stability. Despite evidence alluding to temperature and light instability, many manufacturers and users often disregard these limitations [8]. In a recent study, Emery Pharma performed a comparative temperature stability analysis and identified significant degradation in both CBD and Δ-9-THC content.

Figure 3. Stability analysis of 1 µg/mL CBD and 1 µg/mL Δ-9-THC, at -80 °C and 4 °C.

In addition to its therapeutic uses, CBD and other cannabinoid compounds have been known to exhibit antimicrobial properties against Staphylococcus aureus [9], a pathogenic bacterium with strains that have developed resistance to many common antibiotics, including methicillin. This finding is significant, as the spread of antibiotic resistance has been listed as a matter of “high priority” by the World Health Organization (WHO). Even the Centers for Disease Control and Prevention (CDC) has identified antibiotic resistance as “…one of the world’s most urgent public health problems” [10, 11]. With the emergence of “superbugs”, there is an urgent need for identifying new antimicrobial agents capable of inhibiting the growth of resistant organisms without inducing further resistance. A 2019 study by Dr. Mark Blaskovich from the University of Queensland found that CBD inhibits S. aureus and other Gram-positive bacteria without promoting resistance development [12, 13]. This highlights the potential of CBD as a novel antibiotic candidate for treating multidrug-resistant infections.

Results

Emery Pharma has the capacity to assess antibiotic resistance and has recently completed a comprehensive antimicrobial study for a leading CBD oil company. Their product was a hemp-derived oil extract, which we evaluated to determine the Minimum Inhibitory Concentration (MIC). In antimicrobial drug discovery, MIC screening is a critical first step, defined as the lowest concentration of a compound that inhibits microbial growth. In this case, the CBD oil product was tested on two strains of S. aureus: Methicillin-sensitive (MSSA) and Methicillin-resistant S. aureus (MRSA), both of which are major causes of skin and soft tissue infections. Our results show that the MIC of the hemp oil extract against both MSSA and MRSA is 2 µg/mL (Table 1), which closely aligns with the published CBD MIC values of 0.5–1 µg/mL [9].

Table 1. MIC of hemp-based oil extract against two types of S. aureus.

The next step is to perform a time-kill kinetics assay. For this assay, the hemp extract was tested at 2×, 4×, and 8× MIC, and bacterial density was determined at 0, 6, and 24 hours. A growth control was included to monitor the natural progression of bacterial growth. The results are shown below in Figures 4 and 5.

Figure 4. Time-kill of MSSA by hemp extract.

Figure 5. Time-kill of MRSA by hemp extract.

The CBD hemp extract was able to reduce both MSSA and MRSA from an initial density of ~1,000,000 colony-forming units (CFU)/mL to ≤10 CFU/mL within 6 hours. This represents a 5,000-fold reduction in bacterial load, with no significant regrowth detected after 24 hours.

Conclusion

In addition to our capabilities in antimicrobial activity testing and chemical analysis of cannabis products, Emery Pharma is also capable of extracting and quantifying cannabinoids from various biological matrices, including saliva, plasma, urine, and stool. We also have extensive experience in clinical trial design, PK analysis, and are DEA-licensed to handle Schedule I to V substances, which include cannabis and Δ-9-THC.

With our combined expertise in bioanalytical cannabis testing, antimicrobial screening, cannabinoid PK/PD assessment, and clinical study support, Emery Pharma is ready to help advance your CBD or cannabinoid-based drug development program. If you are interested in any of these services, please call us at +1 (510) 899-8814 or contact us online to get started!

About the Author

Authored by Dr. Ryan Cheu, Director of Chemistry, and Dr. Janet Liu, Director of Biology.

References

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