Abstract

Ophthalmic delivery of dexamethasone can control inflammation and also some forms of uveitis. But it is effective therapeutically over a short period of time and frequent instillation is required. hydroxypropyl methylcellulose matrix films containing dexamethasone were prepared by casting method in presence and absence of particulate kaolin for extending ophthalmic drug delivery. Fourier-transform infrared spectroscopy confirmed the complexation of dexamethasone and kaolin in the film via formation of hydrogen bond and the observed shouldering at 1032 cm^-1 increased with corresponding higher amount of kaolin binding. Differential scanning calorimetry thermogram resulted in almost complete amorphization of dexamethasone in the film. X-ray diffractogram demonstrated almost disappearance of kaolinite diffraction and the reduced order of dexamethasone crystal lattice in all the film formulations. Submicrons, tubular and nano-fibrous morphology of the kaolin and drug particles were seen in the scanning electron microscope images of the film. Relatively extended diffusion controlled drug release and ophthalmic permeation behavior were observed with the increase of kaolin loading in the film. Stable complex facilitated the sustained ophthalmic delivery of dexamethasone and prolonged anti-inflammatory activity. Molecular docking study also revealed the complex formation of dexamethasone with kaolin and hydroxypropyl methyl cellulose to understand the fitting and stable configuration of drug-carrier interaction. Kaolin-based hydroxypropyl methyl cellulose hydrogel film containing dexamethasone as a model drug can enhance the corneal residence time for anti-inflammation for an extended period of time.