Comparative pharmaceutical evaluation of brand and generic clobetasone butyrate ointments

In the present study, we performed comprehensive pharmaceutical evaluation among an original clobetasone butyrate (CLB) ointment product and three generic products. Although spherocrystal images were observed under a polarizing microscope for only Kindavate^®, the original product, distribution of active and inactive ingredients was chemically equivalent between the original and generic medicine by the attenuated total reflection infrared spectroscopy. These results suggest that the spherocrystals observed in Kindavate^® are composed of hydrocarbon. On GC/MS, it was revealed that linear alkanes having 25-27 carbon atoms are densely present in Sun White^®, the base used in Kindavate^®. On the other hand, linear alkanes having 22-31 carbon atoms were broadly distributed in most other white petrolatums. In the CLB ointment products, the distribution equivalent of linear alkane to Sun White^® was observed only in Kindavate^®. Thus, the GC/MS method is extremely useful for identification of white petrolatum used in the ointment. A similar amount of CLB among the pharmaceutical products was detected in the skin tissue by skin accumulation test, although there were the differences in rheological properties and the quality of white petrolatum. The present results will be very useful for pharmacists in selecting medicine products that match the needs of the patient. Such pharmaceutical information will help spread objective knowledge about products in the future, and will contribute to the appropriate selection of medication.