Evaluation of the Amounts of Sennosides A and B in Rhubarb-containing Kampo Medicines to Create a Ranking of Kampo Medicines for Appropriate Selection of Laxatives

OBJECTIVES: To evaluate 20 Kampo medicines, which comprised 6 formulas, Otsujito, Junchoto, Tokakujokito, Bofutsushosan, Mashiningan, and Keishikashakuyakudaioto, from 7 brands, to create a ranking of Kampo medicines for appropriate selection of laxatives. METHODS: The amounts of sennosides A and B, the important components showing laxative effects contained in Kampo medicines, were analysed using High Performance Liquid Chromatography. RESULTS: We found that the amounts of sennosides A and B were different among brands, even when they had the same formula. Furthermore, the amounts of sennosides differed when the same amounts of rhubarb were used. CONCLUSIONS: These results suggest that the differences in amounts of sennosides are caused by the quality of the rhubarb used. Kampo medicines containing laxatives other than rhubarb, including disodium sulphate and hemp seed, had synergistic laxative effects. Thus, in the future, it may be possible to adjust laxative potency of Kampo medicines through further clinical tests.