The facilitation of corneal permeability of cyclosporine A loaded on chitosan-graft-cyclodextrin copolymers vector

Abstract

Objective To investigate the corneal permeability of cyclosprin A (CsA) loaded on polymeric vector after topical application. Methods The grafted copolymer chitosan-graft-cyclodextrin (CS-g-CD) was synthesized, and the physicochemical structures of the polymer were investigated using nuclear magnetic resonance spectroscopy (NMR) and fourier transform infrared spectroscopy (FT-IR). A novel CsA eye drop was prepared using the grafted copolymer as carrier material.The physicochemical properties of eye drop, including drug-loading content, osmotic pressure and viscosity were investigated by high performance liquid chromatography-mass spectrometry (HPLC-MS), osmotic pressure gauge and viscometer, respectively.New Zealand albino rabbits were randomly divided into intact cornea CsA group, epithelium debrided CsA group and epithelium debrided control group.The corneal epithelia of the left eyes was debrided in the cornea epithelium debrided group.Cornea irritation test was performed on New Zealand albino rabbits.The aqueous humor was taken and the corneas were collected at 0.5 hour and 1 hour after instilled.The concentration of CsA was measured by HPLC-MS.Cy5 labeled vector loaded with Coumarin 6 served as model copolymers system, the penetration capabilities of the double fluorescent labeling copolymers system were monitored in vivo using two-photon scanning fluorescence microscopy on murine corneas after topical application.The use and care of the animals complied with Regulations for the Administration of Affair Concerning Experimental Animals by State Science and Technology Commission. Results The polymer of CS-g-CD was successfully synthesized and confirmed using NMR and FT-IR.The drug loading of CsA in eye drop solution was 0.06 %; the osmotic pressure was 305 mOsmol/kg and the viscosity was 36.5 cP.The CsA drug delivery system had a reversible temperature-sensitive drug release behavior and had no obvious irritation on the eyes of New Zealand rabbits.One hour after treatment, the concentration of CsA in the cornea and aqueous humor of epithelium debrided CsA group was (5.88±1.46)μg/g and (149.19±3.93)ng/ml, respectively, which was significantly higher than (3.98±0.95)μg/g and (30.25±11.43)ng/ml in epithelium debrided control group (both at P<0.05); the concentration of CsA in the aqueous humor of intact cornea CsA group was (7.23±1.31)ng/ml, which was significantly lower than that in epithelium debrided CsA group (P<0.05). Polymer vectors were mainly retained in the corneal epithelium, and coumarin 6 gradually diffused into the deep corneal stroma with time. Conclusions The grafted copolymer can load CsA, and the eye drop can effectively overcome the corneal barrier and increase the corneal permeability of CsA. Key words: Cyclosporine A; Immunosuppressive agents; Corneal barrier; Fluorescent double labeling; Corneal tissue distribution