RiceSorb^® as Talcum Substitute for Loose Face Powders: Formulation and Characterization

Excessive and daily inhalation of talcum, a main ingredient of face powders, causes pulmonary talcosis, which has led to the replacement of talcum with safer natural ingredients. RiceSorb^®, or Oryza sativa starch from Japanese rice, was used as an alternative owing to its nontoxic and excellent oil absorption capacity. The objectives of the present work were to formulate loose face powders from RiceSorb^® and to investigate the physicochemical properties of the prepared formulations. Five formulations of loose face powders were prepared by varying the ratios between talcum and RiceSorb^®: 4:0 (FT0), 3:1 (FT1), 1:1 (FT2), 1:3 (FT3), and 0:4 (FT4). The physicochemical properties were evaluated mainly based on USP 41 and NF 36 such as morphology by using a scanning electron microscope, bulk density, flow property (angle of repose), moisture content (MC), and pH. The stability of the formulations were also performed at ambient temperature and 45°C for 2 months. The formulations had pH 6.90-8.62, bulk density 0.33-0.49 g/ml, and an angle of repose 30°-41°. Overall, the formulations which contained only RiceSorb^® (FT4) or higher proportion of RiceSorb^® (FT3) had finer particles, lower bulk density, pH, and angle of repose than those of the formulations containing high proportion of talcum: FT0 and FT1. Under storage conditions for 2 months, the formulations containing high proportion of RiceSorb^® exhibited noticeably increased MC and angle of repose. However, the other physicochemical properties were somewhat the same. The present results suggest the applicability of RiceSorb^® for loose face powders.