In‐depth study of the mucoadhesive and lubricating properties of Hyalistil SYNFO and other sodium hyaluronate‐based eye drops

Abstract

Purpose: Several sodium hyaluronate (SH) eye drops formulations are widely used for the management of dry eye disease (DED). Hyalistil SYNFO is an eye drops based on SH and xanthan gum and osmoprotectants (glycine and betaine). The aim of our study was to evaluate viscosity and mucoadhesion profiles of Hyalistil SYNFO with respect to other SH‐based eye drops, and to investigate their ability to protect the corneal surface from dehydration.Methods: The physicochemical properties, in term of viscoelastic and mucoadhesive behaviour, were evaluated by means of a rheometer, TA‐XT2 texture analyzer and zeta potential determination. An in vitro dehydration model was used to demonstrate the lubricant effect of Hyalistil SYNFO compared to other commercially available SH‐based eye drops on human corneal epithelial cells (HCE).Results: The rheological profiles indicated that Hyalistil SYNFO exhibits a viscoelastic behaviour under shear strain showing a characteristic curve owing to its specific molecular properties. Evaluations of detachment force of tested formulations resulting in a strengthening of the mucin‐formulation interface showed that Hyalistil SYNFO exhibited a stronger and significant mucoadhesion calculated as percentage compared to mucin and other SH‐based products. The occurring interaction between formulation and mucin was also demonstrated by the variations in zeta potential measured by the mucin‐eye drops mixture compared to mucin or product alone. The in vitro study on HCE cells demonstrated that Hyalistil SYNFO, compared to others formulation, was able to protect corneal epithelial cells from dehydration.Conclusions: The pseudoplastic profile and increased mucoadhesive strength, due to the presence of both SH and xanthan gum, may lead to an improved residence time of Hyalistil SYNFO on the corneal epithelium ensuring relief during the treatment of DED. Moreover, the effect against dehydration improves eye lubrication and corneal cell protection.