Molecular Interactions Underlying Dissolution Trends in Cannabidiol-Polymer Amorphous Solid Dispersions

Cannabidiol (CBD) is viewed as promising therapeutic agent against a variety of health ailments; however, its efficacy is limited by poor aqueous solubility. Amorphous solid dispersions (ASDs) can enhance the solubility of therapeutics by distributing it throughout a polymer matrix. In consideration of ASD formulations with CBD, we investigate the interactions of CBD with various polymers: polyvinylpyrrolidone (PVP), polyvinylpyrrolidone/vinyl acetate (PVP/VA) copolymer, hydroxypropyl methylcel- lulose phthalate (HPMCP), hydroxypropyl methylcellulose acetate succinate (HPM- CAS), and poly(methyl methacrylate) (PMMA). Both experiment and molecular dynamics simulation reveal diverse mixing behavior amongst the set of polymers. Detailed structural and nano-scale interaction analyses suggest that positive deviations from ideal-mixing behavior arise from the formation of stable polymer-CBD hydrogen bonds whereas negative deviations are associated with disruptions to the polymer- polymer hydrogen-bond network. Polymer-water interaction analyses indicate the significance of polymer hydrophobicity that can lead to poor dissolution of CBD. These results have implications for drug dissolution rates based on how CBD and water interacts with each polymer. Furthermore, these insights may be used to guide ASD formulations for CBD or other small-molecule therapeutic agents.