Influence of solubility and partition coefficient on the loading of combined poly(isobutylcyanoacrylate) and hydroxypropyl-β-cyclodextrin nanoparticles by steroids

Combined poly(isobutylcyanoacrylate) and cyclodextrin nanoparticles have recently been prepared by polymerization of the monomer in the presence of cyclodextrins. The association of large amounts of cyclodextrins with particles was likely to modify not only loading of the particles during the polymerization process but also the lipophilicity of the polymer, because of introducing numerous lipophilic sites into the particle structure. In a series of corticosteroids spanning a broad range of water solubility and lipophilicity values, it has been shown that drug loading of combined nanoparticles were increased up to 120-fold when compared to standard poly(isobutylcyanoacrylate) particles. The ability of the drug to achieve a high level of particle loading depended both on the drug concentration in the polymerization medium and on the octanol-water partition coefficient. It was therefore concluded that the drug loading of the combined nanoparticles was driven by the partition equilibrium between the polymeric structure and the polymerization medium.