Biodegradable hybrid polymeric membranes for ocular drug delivery

Ophthalmic delivery systems such as ocular inserts are useful strategies to improve the ocular bioavailability of topically administered drugs. In the present study polyvinyl alcohol and sodium carboxymethylcellulose based ocular inserts were prepared by solution casting for sustained drug delivery of ciprofloxacin for treatment of topical infections. The polymers were esterified and the formation of ester bonds was confirmed by Fourier transform infrared spectroscopy. The inserts had a smooth structure with a surface roughness of 7.3 nm. Inserts were found to be wettable by simulated tear fluid with contact angle <45°. Mechanical testing results indicated that the tensile strength of polyvinyl alcohol–sodium carboxymethylcellulose (10:2 wt.%) inserts was up to 8.9 ± 1.9 MPa, which is adequate to resist the pressure likely to be exerted during application. In vitro drug release kinetics showed sustained release of ciprofloxacin for up to 48 h from the inserts. Sodium fluorescein-loaded inserts showed higher penetration of the dye in the posterior segment tissues of explanted goat eye balls as compared with an eye drop solution of sodium fluorescein. The inserts were non-toxic to corneal epithelial cells and showed no signs of acute ocular toxicity in in vivo studies in albino rabbits.