In vitro evaluation of the mucoadhesive properties of zinc hyaluronate

Zinc hyaluronate (HA-Zn) is a polymeric salt that combines the unique properties of natural hyaluronic acid (HA) and such a vital element as zinc, which has antimicrobial, antiviral, antifungal, and antioxidant properties. For therapeutic purposes, the HA-Zn substance (in various formulations) is used mainly in contact with biological surfaces, including mucous membranes, and increased mucoadhesiveness can provide prolonged local action of this substance. Using porcine stomach mucin (type III) and turbidimetric titration at pH 2.0, 4.0, 6.5 and 8.0, this study was aimed to evaluate the mucoadhesiveness of HA-Zn at low concentrations in aqueous solutions (0.1-1.0 mg/mL). For comparison, the HA sodium salt (HA-Na) mucoadhesiveness was tested. The results showed that HA-Zn, unlike HA-Na, exhibited mucoadhesive properties at all pH values, and the strongest mucoadhesiveness was observed under acidic conditions at the HA-Zn concentration of ≥0.78 mg/mL and HA-Zn/mucin weight ratios of 1.0-1.1 and higher.