Abstract
TiO2 has been widely used in pharmaceutical products, and it also has been used as a photocatalyst. In this study, the influence of photocatalytic activity on the stability of solid-state mequitazine, an H1-blocker, was investigated. The photo-degradation of mequitazine with TiO2 occurred under irradiation with both light sources. The degree of degradation of mequitazine with anatase was higher than that of rutile. The degradation was significantly enhanced with increasing relative humidity. The relationship between the apparent degradation rate constant and water vapor pressure could be clearly described by a simple power law. The major photo-degradation products of mequitazine, resulting from photocatalytic activity of TiO2, were mequitazine-S-oxide and mequitazine-sulphone. A remarkable degradation of mequitadine occurred with addition of TiO2, and its photocatalytic activity was controlled by water vapor pressure. The photo-degradation of mequitazine with TiO2 is a different process from mequitazine without TiO2, because mequitazine-S-oxide and mequitazine-sulphone are not formed with normal photo-degradation of mequitazine.
