Copolymerized Polymers Based on Cyclodextrins and Cationic Groups Enhance Therapeutic Effect of Rebamipide in the N-Acetylcysteine-Treated Dry Eye Model

Hiroko Otake,1,* Ko Kobayashi,2,* Reita Kadowaki,1 Taiyo Kosaka,1 Mizuki Itahashi,1 Masanobu Tsubaki,1 Masaru Matsuda,2 Norio Iwakiri,2 Eiji Harata,2 Noriaki Nagai1 1Faculty of Pharmacy, Kindai University, Osaka, Japan; 2Life Science Division, NOF CORPORATION, Kanagawa, Japan*These authors contributed equally to this workCorrespondence: Noriaki Nagai, Faculty of Pharmacy, Kindai University, 3-4-1 Kowakae, Higashi-Osaka, Osaka, 577-8502, Japan, Tel +81 6 4307 3638, Fax +81 6 6730 1394, Email [email protected]: We aimed to prepare a β-cyclodextrin (β-CD) polymer using radical polymerization with co-monomers, 6-deoxy-6-(2-methacryloyloxyethylsuccinamide)-β-cyclodextrin (CD-MSAm) and N,N,N-trimethyl-N-(2-hydroxy-3-metacryloyloxopropyl)-ammonium chloride (QA) to design cyclodextrins suitable for use in ophthalmology. In addition, we evaluated their solubility and inclusion properties with rebamipide (REB), a poorly soluble drug, and investigated the usefulness of the β-CD polymer and REB (REB@CDQA) combination in treating dry eye.Methods: The β-CD polymer (CD-MSAm-co-QA, CDQA) based on CD-MSAm/QA was prepared via radical polymerization, and the usefulness of REB@CDQA in treating dry eye was evaluated using a rabbit treated with N-acetylcysteine (dry eye model).Results: The solubility of the CDQA powder was higher than that of the β-CD powder, and 80 nm colloids were observed in the CDQA solution. No corneal toxicity was observed in human corneal epithelial cells or rat corneas treated with 0.2% CDQA solution. The levels of REB dissolved in the CDQA solution were higher than those of the β-CD solution. Moreover, the application of the CDQA solution enhanced REB retention in the cornea and attenuated the transcorneal penetration of REB. In addition, instillation of REB@CDQA enhanced the volume of the lacrimal fluid and normalized the reduced mucin levels in the dry eye model. The extent of tear film breakup was attenuated by REB@CDQA instillation.Conclusion: The CDQA solution enhanced the solubility of REB, and the combination of CDQA and REB enhanced the drug content in the corneal tissue. Moreover, the therapeutic effect on dry eye was higher than that of REB suspensions without CDQA. Keywords: β-cyclodextrin, polymer, cationic group, rebamipide, dry eye