The dosage of crude drugs described in the
Shanghanlun has long been discussed, and a conversion ratio for 1 liang in the
Songban Shanghanlun into modern grams has not been established yet.
Ekisai Kariya, a bibliologist in Edo period Japan, claimed that the formulas in the
Songban Shanghanlun could not be decocted when weighed with the “Han shu (lu li zhi)” scale (1 liang = 14 g, “regular scale”), and the weight scale in the text should be “Scale of Shen nong” (1/10 scale of the regular scale). This claim leads to the standards for Kampo prescription dosages. We inspected this matter by focusing on the amount of liquid absorbed by decoction residues, and demonstrated that the formulas in
Songban Shanghanlun could actually be decocted when weighed with the “regular scale”. In addition, we calculated the quantities of Ephedra-alkaloids in the one-time dose of “Ma huang tang” of the several books written in the Song period, and the
Songban Shanghanlun text, with results showing that Chinese doctors in the Song period recognized 1 liang in the
Songban Shanghanlun as 14 grams in modern terms, and that the “regular scale” could be applied clinically. This strongly suggests that the metrological standard in the
Songban Shanghanlun should be the “regular scale”.
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