General selection criteria for safety and patient benefit [XⅢ]: Comparing the formulation characteristics of brand-name and generic bifonazole creams.

Abstract

A comparative evaluation of the brand-name drug Mycospor and six generic drugs (IWAKI, Bifonol, F, YD, Sawai, and TEVA), all comprising a cream formulation containing the antifungal drug bifonazole, was performed based on physicochemical measurements. The pH of the various formulations was significantly higher for the generics Bifonol (pH 7.1), Sawai (pH 6.7), and TEVA (pH 7.3) and significantly lower for YD (pH 4.3) than for the brand-name drug Mycospor (pH 5.5). The viscosity of the various formulations was significantly higher for TEVA (25,011 mPa·s) versus Mycospor (22,376 mPa·s) and significantly lower for IWAKI, Bifonol, F, YD, and Sawai, with Bifonol (8,572 mPa·s) being particularly low. Considering the hysteresis loop area obtained for the shear rate vs. shear stress, which represents the thixotropic properties, and using the value of Mycospor as the reference for 100%, YD (179%), Sawai (557%), and TEVA (201%) showed significantly higher values. Furthermore, the membrane permeability of bifonazole at 24 hours was significantly higher for Bifonol (309 μg/mL) and F (182 μg/mL) and significantly lower for Sawai (124 μg/mL) and TEVA (92 μg/mL) than for Mycospor (153 μg/mL). Finally, optical micrographs showed that the dispersion of particles was similar in the various formulations, but the particles of F and TEVA were uniformly dispersed with a smaller particle size than the other formulations. Overall, significant differences were observed in the formulation characteristics between the brand-name drug and generic drugs, which were attributed to differences in the manufacturing process and the types of additives.