Comparison of the Properties of Brand-Name and Generic Nadifloxacin Creams

Yutaka Inoue¹, Miruto Matsumoto¹, Masayuki Kimura¹, Toru Tanaka², Ikuo Kanamoto¹

¹Laboratory of Drug Safety Management, Faculty of Pharmaceutical Sciences, Josai University, Saitama, Japan, ²Laboratory of Biostatistics, Faculty of Pharmaceutical Sciences, Josai University, Saitama, Japan

Key words: nadifloxacin; generic drug; viscosity; excipients.

Summary. Background and Objective. In external preparations, types and ratios of additives are not necessarily the same for brand-name drugs and generic drugs. Thus, the physicochemical properties of preparations may differ despite the fact that they contain the same ingredients or additives. This study examined differences in brand-name and generic versions of nadifloxacin (NFX) creams.

Material and Methods. Three types of NFX creams (NFX-A, NFX-B, and NFX-C) were used. The viscosity of each preparation was determined, its yield value was calculated, and each preparation was subjected to light microscopy, x-ray powder diffraction, and near-infrared absorption spectroscopy.

Results. Comparison of viscosity of different preparations revealed that NFX-B had a lower viscosity than NFX-A and NFX-C (14.5 vs. 24.6 and 17.9 Pa·s). NFX-B also had a lower yield value than NFX-A and NFX-C. Microscopy revealed that NFX-A and NFX-B had satisfactory emulsification although crystallization was observed with NFX-C. Near-infrared absorption spectroscopy revealed changes in the absorption spectra of NFX-B in comparison with those of NFX-A and NFX-C that were due to differences in water content and differences in fat and oil content.

Conclusions. These findings confirmed that there were differences in the viscosity and flattening of NFX-A, NFX-B, and NFX-C. In addition, microscopy revealed differences in emulsification and it revealed the precipitation of NFX crystals in NFX-C. Near-infrared absorption spectroscopy revealed that differences in the type and amount of additives and water content in the creams had contributed to differences in the preparations.

Correspondence to Y. Inoue, Laboratory of Drug Safety Management, Faculty of Pharmaceutical Sciences, Josai University; 1-1 Keyakidai, Sakado-shi, Saitama, 3500295, Japan. E-mail: yinoue@josai.ac.jp

Received 5 March 2011, accepted 30 November 2011