Comparison of pharmaceutical properties among clobetasol propionate cream formulations: Considerations from near infrared spectra

The purpose of this study is to verify the usefulness of near infrared (NIR) spectroscopy for evaluation of pharmaceutical properties of cream formulations. The present study examined in detail the pharmaceutical properties of clobetasol propionate (CLB) cream formulations using NIR spectroscopy. The characteristic NIR spectrum of Dermovate^® (DRM), the original CLB cream formulation displayed a shoulder around 4800 cm⁻¹ as well as absorption around 5200 cm⁻¹. A high concentration of propylene glycol (PG) in DRM was thought to be the main contributing factor to this characteristic aspect of the spectrum. Only a peak with absorption around 5200 cm⁻¹ was obtained from the generic CLB creams, except for Myalone^® (MYA), suggesting a lower concentration of PG in those generic formulations compared to the original formulation. The spectrum obtained from the analysis of MYA was significantly different from the other formulations. The fact that it contained macrogol and a high PG concentration were likely the major factors that accounted for the spectral differences. High concentrations (25–30%) of PG were found in DRM and MYA by gas chromatography–mass spectrometry. Thus, even cream formulations with the same active pharmaceutical ingredients can have significantly different pharmaceutical properties. And it is suggested usefulness of NIR spectroscopy for evaluation of pharmaceutical property of cream formulation.