In Vivo Pharmacodynamic and Pharmacokinetic Assessment of Cannabidiol-loaded Camel Milk Exosomes in Doxorubicin-resistant Triple-negative Breast Cancer Xenografts

Cannabidiol (CBD) suffers from poor aqueous solubility and extensive first-pass metabolism, which significantly limits its oral bioavailability. In our earlier work, we developed camel milk-derived exosomes (CMDE) as nanocarriers to enhance CBD bioavailability, confirmed through in vivo pharmacokinetic evaluations. In this study, we further characterized the formulation by performing an in silico physiologically based pharmacokinetic (PBPK) simulation using GastroPlus™, integrating in vitro dissolution data. The simulation demonstrated that CBD absorption improved markedly with exosomal encapsulation, achieving 97.8% compared to 13.1% for free CBD. Additionally, CBD-exosomes produced an 8.66-fold increase in maximum plasma concentration (Cmax) and a 7.15-fold increase in the area under the curve (AUC), with predominant uptake observed in the duodenum and jejunum. These computational findings closely mirrored our in vivo results, providing mechanistic insights into the enhanced oral absorption of CBD via exosomal encapsulation. Furthermore, in vitro cytotoxicity studies revealed that combining CBD-CMDE with Paclitaxel (PTX) produced synergistic effects, enabling a two-fold reduction in the required PTX dose. In MDA-MB-231 DOX RT xenograft models, the combination of CBD-CMDE and PTX reduced tumor burden by 2.5-fold relative to controls. Western blot analyses indicated significant downregulation of PI3K/AKT/mTOR pathway regulators, along with modulation of immune markers, suggesting an immune-activating component. Whole-body imaging further confirmed the in vivo targetability of CMDE. This study represents the first application of PBPK modeling, based on in vitro dissolution data, to assess the pharmacokinetics of CBD-exosomes. By integrating computational and preclinical evidence, our findings underscore the potential of exosome-based oral drug delivery systems in enhancing therapeutic efficacy.

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