The effects of bivalent inorganic salts on the mucoadhesive performance of a polymethylmethacrylate sodium salt

The effects of bivalent inorganic salts, namely CaCl2, MgCl2, MgSO4, ZnCl2, and ZnSO4, on the mucoadhesive performance of a polymethylmethacrylate sodium salt (EuSNa) were investigated. The swelling properties and mucoadhesion of ten different blends made of EuSNa and 5 or 10% (m/m) inorganic salts were evaluated. Only the addition of Zn salts caused a significant reduction of mucoadhesive properties and an increase of swelling. Swelling and mucoadhesive properties of the linear polymethylmethacrylate salt were affected by a physical cross-linking due to bivalent cations. The extent of such interaction may be mainly ascribed to the different electronegativity of the bivalent cations. Attenuated total reflectance infrared spectroscopy (ATR-FTIR) and texture analysis supported this hypothesis. Adding magnesium and calcium salts, the intrinsic dissolution rate of EuSNa decreased of at least 25%. Mucoadhesive tablets were prepared with the most suitable blends and tested on human healthy volunteers. The addition of the magnesium and calcium increased the in vivo permanence time without affecting the mucoadhesive performances. The lack of swelling, mucosal irritation and unpleasant sensation allow the use of such blends in the preparation of mucoadhesive tablets. (C) 2005 Elsevier B.V. All rights reserved.