Disposition of glycyrrhetic acid and its glycosides in healthy subjects and patients with pseudoaldosteronism.

ABSTRACT

As a first step to elucidate the disposition of traditional Chinese formulations which contain licorice, the disposition of plain licorice was investigated in humans. Glycyrrhetic acid (GLA) was measured by an enzyme immuno-antibody technique. Glycyrrhetic glycosides (GLA-GS), such as glycyrrhizin, were measured after acid hydrolysis to GLA by the enzyme immuno-antibody assay. Five normal subjects were orally administered a decoction of licorice containing 133 mg of glycyrrhizin. It was found that the time required for maximum serum concentration of GLA-GS was less than 4 h after the administration. Although there were large individual differences, it was found that GLA-GS was eliminated from the blood for the most part within 72 h. On the other hand, GLA reached maximum serum concentration at about 24 h after administration and in two of the five cases it was still detected in the blood even after 96 h. Urinary excretion of GLA was about 2% of the total dose of glycyrrhizin administered. This suggested that there were great differences among the subjects in the absorption and urinary excretion of GLA-GS. The serum GLA levels in two clinical cases who presented pseudoaldosteronism by licorice containing formulations were as high as 70-80 ng/ml, with GLA-GS levels being very low. This fact suggests that pseudoaldosteronism develops in association with GLA rather than with GLA-GS.