An emulsion delivery system may be affected significantly by oil phase composition in terms of digestion behavior and bioavailability of the delivered substance. In this study, emulsions loaded with cannabidiol (CBD) were prepared with medium chain triglyceride (MCT), long chain triglyceride (LCT) or MCT/LCT(1:1) as carrier oil and whey protein-maltodextrin conjugate as emulsifier, and the digestion behavior of emulsion and bioavailability of CBD were assessed in vitro and in vivo. The particle size of emulsions throughout the in vitro digestion process was in the order of MCT < MCT/LCT < LCT, and three emulsions showed consistent particle size changes: stable in oral phase, sharply increased in gastric phase, and decreased in small intestine. After intestinal digestion, about 90% of free fatty acids (FFA) was released in MCT emulsion, followed by MCT/LCT (76%) and then LCT (45%). CBD was degraded during gastrointestinal digestion and the transformation stability of CBD in oil phase was in the order of LCT > MCT/LCT > MCT. Although CBD had higher bioaccessibility in MCT and MCT/LCT emulsions, the bioavailability of CBD in LCT was the highest (43%), followed by MCT/LCT (39%), MCT (33%). In vivo pharmacokinetic study showed that MCT/LCT and LCT were more favorable for CBD transport and absorption. The results may provide useful information for the construction of delivery systems, protecting CBD molecules, and improving their bioavailability.
Keywords: Bioavailability; Cannabidiol; Emulsion; LCT; MCT; Oil composition.
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