Formulation design of quercetin-loaded polyvinyl alcohol nanofibres for ocular drug delivery

Abstract

In the realm of ocular drug delivery, the limited bioavailability of pharmaceuticals presents a significant challenge. The development of alternative drug delivery systems aimed at enhancing the availability of medications at targeted sites is of considerable importance in addressing this issue. The research work aimed to design, formulate, and optimize a fast-dissolving nanofiber of quercetin and polyvinyl alcohol for an ocular delivery system. Response Surface Methodology (Box-Behnken design) was used for the optimisation of electrospinning parameters, including polymer concentration, flow rate, and voltage, resulting in enhanced drug encapsulation and the formation of smooth and uniform nanofibers. Morphological characterization was conducted using scanning electron microscopy, which demonstrated the development of smooth, uniform, bead-like porous fibers with the drug incorporated within the fibers in nanoform during the electrospinning process, rather than being deposited on the surface. The drug-excipient interaction was evaluated by FTIR analysis, which indicated compatibility between PVA and quercetin, with all the peaks of the quercetin retained in the optimized formulation. The conversion of quercetin from its crystalline form to an amorphous state was demonstrated through X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analyses. The XRD pattern illustrated a reduction in the crystalline peaks characteristic of quercetin, while the DSC results indicated a decrease in the melting point of quercetin in nanofibers. The physical, chemical, and pharmaceutical characteristics of the optimized nanofibre formulation were appropriate and within limits. Disintegration was accomplished within 45 s, with approximately 100% of the active ingredient released within 10 min during an in vitro dissolution test. In contrast, the conventional eye drop formulation exhibited a release of only 50%. Eye irritation study results indicated that there was no visual sign of irritation in all experimental rabbits. The optimized formulation underwent an accelerated stability study and retained its original properties with negligible changes. There was no significant alteration in physical appearance, flexibility, disintegration time, or drug encapsulation, confirming its stability.