Purpose:
To evaluate how polyethylene glycol (PEG) hydrogels used in ophthalmology interact with fluoroquinolone antibiotics and corneal epithelial cells in vitro.
Methods:
In-situ gel-forming hydrogels are licensed for use on the ocular surface in the UK and Europe, however little is known about how they interact with corneal epithelial cells and antibiotics. 40 uL hydrogel 'micro-discs' designed to simulate the typical volume see on the ocular surface were soaked in 0.3% ofloxacin, 0.3% ciprofloxacin, 0.5% levofloxacin and 0.5% moxifloxacin, then placed in phosphate buffered saline and sampled at regular intervals until equilibrium was reached. Concentrations were determined using UV spectrometry. Corneal tissue modelling with compressed collagen gels and in vitro cell culture are used to demonstrate the interaction of PEG hydrogels with corneal epithelial cells.
Results:
All 4 quinolones were absorbed in significant amounts by the hydrogel with the maximum being 0.4mg of moxifloxacin. Assuming tear film clearance is the method of dissolution, minimum inhibitory concentration of antibiotic (MIC90) would be sustained for 5-6 hours after administration. Fluorescent microscopy demonstrated healthy corneal epithelial cell morphology when cultured on compressed collagen gels and covered with PEG hydrogel. Epithelial cells were unable to grow across the surface of PEG hydrogel thereby avoiding encapsulation within the hydrogel.
Conclusions:
Results suggest that instillation of fluoroquinolones in the presence of PEG hydrogel on the ocular surface may promote a sustained-release effect. In situ gel-forming PEG hydrogels can be used without fear of damaging healthy corneal epithelial cells or creating potential problems with hydrogel encapsulation.
Keywords: cornea: epithelium • cornea: basic science