RESUMO
Kikisui is a herbal lotion containing Kochia scoparia Fruit and Cnidium monnieri Fruit that is clinically used as an antipruritic for itchy dry skin. However, this formulation is unsuitable for inducing a prolonged effect. Here, we attempted to change the formulation from a lotion to a cream. The cream we chose was a water-in-oil (W/O) type emulsion for enhancing skin compatibility. In addition, the high water content imparts a sensation of coolness. However, it is difficult to prepare a stable W/O type cream with high water content using a mechanical mixing method. Instead, we prepared the W/O type emulsion using liquid crystals. Water containing cocamidopropyl betaine was added to a dispersed phase comprising an oil phase of oleic acid and liquid paraffin that was constantly stirred. Addition of an aqueous solution containing Kochia scoparia Fruit and Cnidium monnieri Fruit decreased the stability of the cream. However, addition of glycerin as a humectant, and ethyl p-hydroxybenzoate/n-butyl p-hydroxybenzoate as preservatives enhanced the stability of the cream. The stability of the emulsion was correlated with the apparent viscosity of the cream. The final W/O type cream had a water content of 83% and was stable for more than 6 months at 4°C. Furthermore, ostol, which is one of the main biologically active herbal compounds, was also stable for more than 6 months.