Stabilization of sulfisomidine tablets by use of film coating containing UV absorber: Protection of coloration and photolytic degradation from exaggerated light.

The effect of model polymer coating films of vinyl acetate, containing oxybenzone as a UV absorber, on the coloration and photolytic degradation of simple sulfisomidine tablets was examined to attempt stabilization of photosensitive solid dosage forms. Coloration of the tablet surface was followed by the tristimulus colorimetric method in the fading tester equipped with a mercury vapor lamp. Photolytic degradation in the UV region was investigated by a new method for measuring the absorption spectra of a crystal sample in the gas phase, i.e., the semi-integral attenuance spectra. Two parameters of a film, thickness and concentration of the UV absorber, were varied at every exposure. These physical and chemical changes are discussed in relation to light transmission properties of films.